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What is (are) congenital central hypoventilation syndrome ? | Congenital central hypoventilation syndrome (CCHS) is a disorder that affects breathing. People with this disorder take shallow breaths (hypoventilate), especially during sleep, resulting in a shortage of oxygen and a buildup of carbon dioxide in the blood. Ordinarily, the part of the nervous system that controls involuntary body processes (autonomic nervous system) would react to such an imbalance by stimulating the individual to breathe more deeply or wake up. This reaction is impaired in people with CCHS, and they must be supported with a machine to help them breathe (mechanical ventilation) or a device that stimulates a normal breathing pattern (diaphragm pacemaker). Some affected individuals need this support 24 hours a day, while others need it only at night. Symptoms of CCHS usually become apparent shortly after birth. Affected infants hypoventilate upon falling asleep and exhibit a bluish appearance of the skin or lips (cyanosis). Cyanosis is caused by lack of oxygen in the blood. In some milder cases, CCHS may be diagnosed later in life. In addition to the breathing problem, people with this disorder may have difficulty regulating their heart rate and blood pressure, for example in response to exercise or changes in body position. They may have abnormalities in the nerves that control the digestive tract (Hirschsprung disease), resulting in severe constipation, intestinal blockage, and enlargement of the colon. They are also at increased risk of developing certain tumors of the nervous system called neuroblastomas, ganglioneuromas, and ganglioneuroblastomas. Some affected individuals develop learning difficulties or other neurological problems, which may be worsened by oxygen deprivation if treatment to support their breathing is not completely effective. Individuals with CCHS usually have eye abnormalities, including a decreased response of the pupils to light. They also have decreased perception of pain, low body temperature, and occasional episodes of profuse sweating. People with CCHS, especially children, may have a characteristic appearance with a short, wide, somewhat flattened face often described as "box-shaped." Life expectancy and the extent of any cognitive disabilities depend on the severity of the disorder, timing of the diagnosis, and the success of treatment. | congenital central hypoventilation syndrome |
How many people are affected by congenital central hypoventilation syndrome ? | CCHS is a relatively rare disorder. Approximately 1,000 individuals with this condition have been identified. Researchers believe that some cases of sudden infant death syndrome (SIDS) or sudden unexplained death in children may be caused by undiagnosed CCHS. | congenital central hypoventilation syndrome |
What are the genetic changes related to congenital central hypoventilation syndrome ? | Mutations in the PHOX2B gene cause CCHS. The PHOX2B gene provides instructions for making a protein that acts early in development to help promote the formation of nerve cells (neurons) and regulate the process by which the neurons mature to carry out specific functions (differentiation). The protein is active in the neural crest, which is a group of cells in the early embryo that give rise to many tissues and organs. Neural crest cells migrate to form parts of the autonomic nervous system, many tissues in the face and skull, and other tissue and cell types. Mutations are believed to interfere with the PHOX2B protein's role in promoting neuron formation and differentiation, especially in the autonomic nervous system, resulting in the problems regulating breathing and other body functions that occur in CCHS. | congenital central hypoventilation syndrome |
Is congenital central hypoventilation syndrome inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. More than 90 percent of cases of CCHS result from new mutations in the PHOX2B gene. These cases occur in people with no history of the disorder in their family. Occasionally an affected person inherits the mutation from one affected parent. The number of such cases has been increasing as better treatment has allowed more affected individuals to live into adulthood. About 5 to 10 percent of affected individuals inherit the mutation from a seemingly unaffected parent with somatic mosaicism. Somatic mosaicism means that some of the body's cells have a PHOX2B gene mutation, and others do not. A parent with mosaicism for a PHOX2B gene mutation may not show any signs or symptoms of CCHS. | congenital central hypoventilation syndrome |
What are the treatments for congenital central hypoventilation syndrome ? | These resources address the diagnosis or management of CCHS: - Gene Review: Gene Review: Congenital Central Hypoventilation Syndrome - Genetic Testing Registry: Congenital central hypoventilation - MedlinePlus Encyclopedia: Hirschsprung's Disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | congenital central hypoventilation syndrome |
What is (are) MPV17-related hepatocerebral mitochondrial DNA depletion syndrome ? | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome is an inherited disorder that can cause liver disease and neurological problems. The signs and symptoms of this condition begin in infancy and typically include vomiting, diarrhea, and an inability to grow or gain weight at the expected rate (failure to thrive). Many affected infants have a buildup of a chemical called lactic acid in the body (lactic acidosis) and low blood sugar (hypoglycemia). Within the first weeks of life, infants develop liver disease that quickly progresses to liver failure. The liver is frequently enlarged (hepatomegaly) and liver cells often have a reduced ability to release a digestive fluid called bile (cholestasis). Rarely, affected children develop liver cancer. After the onset of liver disease, many affected infants develop neurological problems, which can include developmental delay, weak muscle tone (hypotonia), and reduced sensation in the limbs (peripheral neuropathy). Individuals with MPV17-related hepatocerebral mitochondrial DNA depletion syndrome typically survive only into infancy or early childhood. MPV17-related hepatocerebral mitochondrial DNA depletion syndrome is most frequently seen in the Navajo population of the southwestern United States. In this population, the condition is known as Navajo neurohepatopathy. People with Navajo neurohepatopathy tend to have a longer life expectancy than those with MPV17-related hepatocerebral mitochondrial DNA depletion syndrome. In addition to the signs and symptoms described above, people with Navajo neurohepatopathy may have problems with sensing pain that can lead to painless bone fractures and self-mutilation of the fingers or toes. Individuals with Navajo neurohepatopathy may lack feeling in the clear front covering of the eye (corneal anesthesia), which can lead to open sores and scarring on the cornea, resulting in impaired vision. The cause of these additional features is unknown. | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome |
How many people are affected by MPV17-related hepatocerebral mitochondrial DNA depletion syndrome ? | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome is thought to be a rare condition. Approximately 30 cases have been described in the scientific literature, including seven families with Navajo neurohepatopathy. Within the Navajo Nation of the southwestern United States, Navajo neurohepatopathy is estimated to occur in 1 in 1,600 newborns. | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome |
What are the genetic changes related to MPV17-related hepatocerebral mitochondrial DNA depletion syndrome ? | As the condition name suggests, mutations in the MPV17 gene cause MPV17-related hepatocerebral mitochondrial DNA depletion syndrome. The protein produced from the MPV17 gene is located in the inner membrane of cell structures called mitochondria. Mitochondria are involved in a wide variety of cellular activities, including energy production, chemical signaling, and regulation of cell growth, division, and death. Mitochondria contain their own DNA, known as mitochondrial DNA (mtDNA), which is essential for the normal function of these structures. It is likely that the MPV17 protein is involved in the maintenance of mtDNA. Having an adequate amount of mtDNA is essential for normal energy production within cells. MPV17 gene mutations that cause MPV17-related hepatocerebral mitochondrial DNA depletion syndrome lead to production of a protein with impaired function. One mutation causes all cases of Navajo neurohepatopathy and results in the production of an unstable MPV17 protein that is quickly broken down. A dysfunctional or absent MPV17 protein leads to problems with the maintenance of mtDNA, which can cause a reduction in the amount of mtDNA (known as mitochondrial DNA depletion). Mitochondrial DNA depletion impairs mitochondrial function in many of the body's cells and tissues, particularly the brain, liver, and other tissues that have high energy requirements. Reduced mitochondrial function in the liver and brain lead to the liver failure and neurological dysfunction associated with MPV17-related hepatocerebral mitochondrial DNA depletion syndrome. Researchers suggest that the less mtDNA that is available in cells, the more severe the features of Navajo neurohepatopathy. | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome |
Is MPV17-related hepatocerebral mitochondrial DNA depletion syndrome inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome |
What are the treatments for MPV17-related hepatocerebral mitochondrial DNA depletion syndrome ? | These resources address the diagnosis or management of MPV17-related hepatocerebral mitochondrial DNA depletion syndrome: - Gene Review: Gene Review: MPV17-Related Hepatocerebral Mitochondrial DNA Depletion Syndrome - Genetic Testing Registry: Navajo neurohepatopathy - The United Mitochondrial Disease Foundation: Treatments and Therapies These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | MPV17-related hepatocerebral mitochondrial DNA depletion syndrome |
What is (are) Loeys-Dietz syndrome ? | Loeys-Dietz syndrome is a disorder that affects the connective tissue in many parts of the body. Connective tissue provides strength and flexibility to structures such as bones, ligaments, muscles, and blood vessels. There are four types of Loeys-Dietz syndrome, labelled types I through IV, which are distinguished by their genetic cause. Regardless of the type, signs and symptoms of Loeys-Dietz syndrome can become apparent anytime in childhood or adulthood, and the severity is variable. Loeys-Dietz syndrome is characterized by enlargement of the aorta, which is the large blood vessel that distributes blood from the heart to the rest of the body. The aorta can weaken and stretch, causing a bulge in the blood vessel wall (an aneurysm). Stretching of the aorta may also lead to a sudden tearing of the layers in the aorta wall (aortic dissection). People with Loeys-Dietz syndrome can also have aneurysms or dissections in arteries throughout the body and have arteries with abnormal twists and turns (arterial tortuosity). Individuals with Loeys-Dietz syndrome often have skeletal problems including premature fusion of the skull bones (craniosynostosis), an abnormal side-to-side curvature of the spine (scoliosis), either a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum), an inward- and upward-turning foot (clubfoot), flat feet (pes planus), or elongated limbs with joint deformities called contractures that restrict the movement of certain joints. Degeneration of the discs that separate the bones of the spine (vertebrae), often affecting the neck, is a common finding. Some affected individuals have prominent joint inflammation (osteoarthritis) that commonly affects the knees and the joints of the hands, wrists, and spine. People with Loeys-Dietz syndrome may bruise easily and develop abnormal scars after wound healing. The skin is frequently described as translucent, often with stretch marks (striae) and visible underlying veins. Other characteristic features include widely spaced eyes (hypertelorism), a split in the soft flap of tissue that hangs from the back of the mouth (bifid uvula), and an opening in the roof of the mouth (cleft palate). Individuals with Loeys-Dietz syndrome frequently develop immune system-related problems such as food allergies, asthma, or inflammatory disorders such as eczema or inflammatory bowel disease. | Loeys-Dietz syndrome |
How many people are affected by Loeys-Dietz syndrome ? | The prevalence of Loeys-Dietz syndrome is unknown. Loeys-Dietz syndrome types I and II appear to be the most common forms. | Loeys-Dietz syndrome |
What are the genetic changes related to Loeys-Dietz syndrome ? | The four types of Loeys-Dietz syndrome are distinguished by their genetic cause: mutations in the TGFBR1 gene cause type I, mutations in the TGFBR2 gene cause type II, mutations in the SMAD3 gene cause type III, and mutations in the TGFB2 gene cause type IV. These four genes play a role in cell signaling that promotes growth and development of the body's tissues. This signaling pathway also helps with bone and blood vessel development and plays a part in the formation of the extracellular matrix, an intricate lattice of proteins and other molecules that forms in the spaces between cells. Mutations in the TGFBR1, TGFBR2, TGFB2, and SMAD3 genes result in the production of proteins with little or no function. Even though these proteins have severely reduced function, cell signaling occurs at an even greater intensity than normal. Researchers speculate that the activity of proteins in this signaling pathway is increased to compensate for the protein whose function is reduced; however, the exact mechanism responsible for the increase in signaling is unclear. The overactive signaling pathway disrupts the development of connective tissue, the extracellular matrix, and various body systems, leading to the varied signs and symptoms of Loeys-Dietz syndrome. | Loeys-Dietz syndrome |
Is Loeys-Dietz syndrome inherited ? | Loeys-Dietz syndrome is considered to have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In about 75 percent of cases, this disorder results from a new gene mutation and occurs in people with no history of the disorder in their family. In other cases, an affected person inherits the mutation from one affected parent. | Loeys-Dietz syndrome |
What are the treatments for Loeys-Dietz syndrome ? | These resources address the diagnosis or management of Loeys-Dietz syndrome: - Gene Review: Gene Review: Loeys-Dietz Syndrome - Genetic Testing Registry: Loeys-Dietz syndrome - Genetic Testing Registry: Loeys-Dietz syndrome 1 - Genetic Testing Registry: Loeys-Dietz syndrome 2 - Genetic Testing Registry: Loeys-Dietz syndrome 3 - Genetic Testing Registry: Loeys-Dietz syndrome 4 - Johns Hopkins Medicine: Diagnosis of Craniosynostosis - MedlinePlus Encyclopedia: Aortic Dissection - National Heart Lung and Blood Institute: How Is an Aneurysm Treated? These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Loeys-Dietz syndrome |
What is (are) N-acetylglutamate synthase deficiency ? | N-acetylglutamate synthase deficiency is an inherited disorder that causes ammonia to accumulate in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia. N-acetylglutamate synthase deficiency may become evident in the first few days of life. An infant with this condition may be lacking in energy (lethargic) or unwilling to eat, and have a poorly controlled breathing rate or body temperature. Some babies with this disorder may experience seizures or unusual body movements, or go into a coma. Complications of N-acetylglutamate synthase deficiency may include developmental delay and intellectual disability. In some affected individuals, signs and symptoms of N-acetylglutamate synthase deficiency are less severe, and do not appear until later in life. Some people with this form of the disorder cannot tolerate high-protein foods such as meat. They may experience sudden episodes of ammonia toxicity, resulting in vomiting, lack of coordination, confusion or coma, in response to illness or other stress. | N-acetylglutamate synthase deficiency |
How many people are affected by N-acetylglutamate synthase deficiency ? | N-acetylglutamate synthase deficiency is a very rare disorder. Only a few cases have been reported worldwide, and the overall incidence is unknown. | N-acetylglutamate synthase deficiency |
What are the genetic changes related to N-acetylglutamate synthase deficiency ? | Mutations in the NAGS gene cause N-acetylglutamate synthase deficiency. N-acetylglutamate synthase deficiency belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of reactions that occurs in liver cells. This cycle processes excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys. The NAGS gene provides instructions for making the enzyme N-acetylglutamate synthase, which helps produce a compound called N-acetylglutamate. This compound is needed to activate another enzyme, carbamoyl phosphate synthetase I, which controls the first step of the urea cycle. In people with N-acetylglutamate synthase deficiency, N-acetylglutamate is not available in sufficient quantities, or is not present at all. As a result, urea cannot be produced normally, and excess nitrogen accumulates in the blood in the form of ammonia. This accumulation of ammonia causes the neurological problems and other signs and symptoms of N-acetylglutamate synthase deficiency. | N-acetylglutamate synthase deficiency |
Is N-acetylglutamate synthase deficiency inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. | N-acetylglutamate synthase deficiency |
What are the treatments for N-acetylglutamate synthase deficiency ? | These resources address the diagnosis or management of N-acetylglutamate synthase deficiency: - Gene Review: Gene Review: Urea Cycle Disorders Overview - Genetic Testing Registry: Hyperammonemia, type III - MedlinePlus Encyclopedia: Hereditary Urea Cycle Abnormality These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | N-acetylglutamate synthase deficiency |
What is (are) desmosterolosis ? | Desmosterolosis is a condition that is characterized by neurological problems, such as brain abnormalities and developmental delay, and can also include other signs and symptoms. Children with desmosterolosis have delayed speech and motor skills (such as sitting and walking). Later in childhood, some affected individuals are able to walk with support; verbal communication is often limited to a few words or phrases. Common brain abnormalities in desmosterolosis include malformation of the tissue that connects the left and right halves of the brain (the corpus callosum) and loss of white matter, which consists of nerve fibers covered by a fatty substance called myelin. People with desmosterolosis commonly have muscle stiffness (spasticity) and stiff, rigid joints (arthrogryposis) affecting their hands and feet. Other features seen in some affected individuals include short stature, abnormal head size (either larger or smaller than normal), a small lower jaw (micrognathia), an opening in the roof of the mouth (cleft palate), involuntary eye movements (nystagmus) or eyes that do not look in the same direction (strabismus), heart defects, and seizures. | desmosterolosis |
How many people are affected by desmosterolosis ? | The prevalence of desmosterolosis is unknown; at least 10 affected individuals have been described in the scientific literature. | desmosterolosis |
What are the genetic changes related to desmosterolosis ? | Desmosterolosis is caused by mutations in the DHCR24 gene. This gene provides instructions for making an enzyme called 24-dehydrocholesterol reductase, which is involved in the production (synthesis) of cholesterol. Cholesterol is a waxy, fat-like substance that can be obtained from foods that come from animals (particularly egg yolks, meat, poultry, fish, and dairy products). It can also be produced in various tissues in the body. For example, the brain cannot access the cholesterol that comes from food, so brain cells must produce their own. Cholesterol is necessary for normal embryonic development and has important functions both before and after birth. DHCR24 gene mutations lead to the production of 24-dehydrocholesterol reductase with reduced activity. As a result, there is a decrease in cholesterol production. Because the brain relies solely on cellular production for cholesterol, it is most severely affected. Without adequate cholesterol, cell membranes are not formed properly and nerve cells are not protected by myelin, leading to the death of these cells. In addition, a decrease in cholesterol production has more severe effects before birth than during other periods of development because of the rapid increase in cell number that takes place. Disruption of normal cell formation before birth likely accounts for the additional developmental abnormalities of desmosterolosis. | desmosterolosis |
Is desmosterolosis inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. | desmosterolosis |
What are the treatments for desmosterolosis ? | These resources address the diagnosis or management of desmosterolosis: - Genetic Testing Registry: Desmosterolosis These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | desmosterolosis |
What is (are) 5-alpha reductase deficiency ? | 5-alpha reductase deficiency is a condition that affects male sexual development before birth and during puberty. People with this condition are genetically male, with one X and one Y chromosome in each cell, and they have male gonads (testes). Their bodies, however, do not produce enough of a hormone called dihydrotestosterone (DHT). DHT has a critical role in male sexual development, and a shortage of this hormone disrupts the formation of the external sex organs before birth. Many people with 5-alpha reductase deficiency are born with external genitalia that appear female. In other cases, the external genitalia do not look clearly male or clearly female (sometimes called ambiguous genitalia). Still other affected infants have genitalia that appear predominantly male, often with an unusually small penis (micropenis) and the urethra opening on the underside of the penis (hypospadias). During puberty, people with this condition develop some secondary sex characteristics, such as increased muscle mass, deepening of the voice, development of pubic hair, and a growth spurt. The penis and scrotum (the sac of skin that holds the testes) grow larger. Unlike many men, people with 5-alpha reductase deficiency do not develop much facial or body hair. Most affected males are unable to father a child (infertile). Children with 5-alpha reductase deficiency are often raised as girls. About half of these individuals adopt a male gender role in adolescence or early adulthood. | 5-alpha reductase deficiency |
How many people are affected by 5-alpha reductase deficiency ? | 5-alpha reductase deficiency is a rare condition; the exact incidence is unknown. Large families with affected members have been found in several countries, including the Dominican Republic, Papua New Guinea, Turkey, and Egypt. | 5-alpha reductase deficiency |
What are the genetic changes related to 5-alpha reductase deficiency ? | Mutations in the SRD5A2 gene cause 5-alpha reductase deficiency. The SRD5A2 gene provides instructions for making an enzyme called steroid 5-alpha reductase 2. This enzyme is involved in processing androgens, which are hormones that direct male sexual development. Specifically, the enzyme is responsible for a chemical reaction that converts the hormone testosterone to DHT. DHT is essential for the normal development of male sex characteristics before birth, particularly the formation of the external genitalia. Mutations in the SRD5A2 gene prevent steroid 5-alpha reductase 2 from effectively converting testosterone to DHT in the developing reproductive tissues. These hormonal factors underlie the changes in sexual development seen in infants with 5-alpha reductase deficiency. During puberty, the testes produce more testosterone. Researchers believe that people with 5-alpha reductase deficiency develop secondary male sex characteristics in response to higher levels of this hormone. Some affected people also retain a small amount of 5-alpha reductase 2 activity, which may produce DHT and contribute to the development of secondary sex characteristics during puberty. | 5-alpha reductase deficiency |
Is 5-alpha reductase deficiency inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the SRD5A2 gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition. Although people who are genetically female (with two X chromosomes in each cell) may inherit mutations in both copies of the SRD5A2 gene, their sexual development is not affected. The development of female sex characteristics does not require DHT, so a lack of steroid 5-alpha reductase 2 activity does not cause physical changes in these individuals. Only people who have mutations in both copies of the SRD5A2 gene and are genetically male (with one X and one Y chromosome in each cell) have the characteristic signs of 5-alpha reductase deficiency. | 5-alpha reductase deficiency |
What are the treatments for 5-alpha reductase deficiency ? | These resources address the diagnosis or management of 5-alpha reductase deficiency: - Genetic Testing Registry: 3-Oxo-5 alpha-steroid delta 4-dehydrogenase deficiency - MedlinePlus Encyclopedia: Ambiguous Genitalia - MedlinePlus Encyclopedia: Intersex These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | 5-alpha reductase deficiency |
What is (are) trisomy 13 ? | Trisomy 13, also called Patau syndrome, is a chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. Individuals with trisomy 13 often have heart defects, brain or spinal cord abnormalities, very small or poorly developed eyes (microphthalmia), extra fingers or toes, an opening in the lip (a cleft lip) with or without an opening in the roof of the mouth (a cleft palate), and weak muscle tone (hypotonia). Due to the presence of several life-threatening medical problems, many infants with trisomy 13 die within their first days or weeks of life. Only five percent to 10 percent of children with this condition live past their first year. | trisomy 13 |
How many people are affected by trisomy 13 ? | Trisomy 13 occurs in about 1 in 16,000 newborns. Although women of any age can have a child with trisomy 13, the chance of having a child with this condition increases as a woman gets older. | trisomy 13 |
What are the genetic changes related to trisomy 13 ? | Most cases of trisomy 13 result from having three copies of chromosome 13 in each cell in the body instead of the usual two copies. The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy 13. Trisomy 13 can also occur when part of chromosome 13 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) or very early in fetal development. Affected people have two normal copies of chromosome 13, plus an extra copy of chromosome 13 attached to another chromosome. In rare cases, only part of chromosome 13 is present in three copies. The physical signs and symptoms in these cases may be different than those found in full trisomy 13. A small percentage of people with trisomy 13 have an extra copy of chromosome 13 in only some of the body's cells. In these people, the condition is called mosaic trisomy 13. The severity of mosaic trisomy 13 depends on the type and number of cells that have the extra chromosome. The physical features of mosaic trisomy 13 are often milder than those of full trisomy 13. | trisomy 13 |
Is trisomy 13 inherited ? | Most cases of trisomy 13 are not inherited and result from random events during the formation of eggs and sperm in healthy parents. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 13. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each cell of the body. Translocation trisomy 13 can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 13 and another chromosome. These rearrangements are called balanced translocations because there is no extra material from chromosome 13. A person with a balanced translocation involving chromosome 13 has an increased chance of passing extra material from chromosome 13 to their children. | trisomy 13 |
What are the treatments for trisomy 13 ? | These resources address the diagnosis or management of trisomy 13: - Genetic Testing Registry: Complete trisomy 13 syndrome - MedlinePlus Encyclopedia: Trisomy 13 These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | trisomy 13 |
What is (are) cone-rod dystrophy ? | Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate. The first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. As the condition progresses, individuals may develop involuntary eye movements (nystagmus). There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, or X-linked (each of which is described below). Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body. | cone-rod dystrophy |
How many people are affected by cone-rod dystrophy ? | Cone-rod dystrophy is estimated to affect 1 in 30,000 to 40,000 individuals. | cone-rod dystrophy |
What are the genetic changes related to cone-rod dystrophy ? | Mutations in approximately 30 genes are known to cause cone-rod dystrophy. Approximately 20 of these genes are associated with the form of cone-rod dystrophy that is inherited in an autosomal recessive pattern. Mutations in the ABCA4 gene are the most common cause of autosomal recessive cone-rod dystrophy, accounting for 30 to 60 percent of cases. At least 10 genes have been associated with cone-rod dystrophy that is inherited in an autosomal dominant pattern. Mutations in the GUCY2D and CRX genes account for about half of these cases. Changes in at least two genes cause the X-linked form of the disorder, which is rare. The genes associated with cone-rod dystrophy play essential roles in the structure and function of specialized light receptor cells (photoreceptors) in the retina. The retina contains two types of photoreceptors, rods and cones. Rods are needed for vision in low light, while cones provide vision in bright light, including color vision. Mutations in any of the genes associated with cone-rod dystrophy lead to a gradual loss of rods and cones in the retina. The progressive degeneration of these cells causes the characteristic pattern of vision loss that occurs in people with cone-rod dystrophy. Cones typically break down before rods, which is why sensitivity to light and impaired color vision are usually the first signs of the disorder. (The order of cell breakdown is also reflected in the condition name.) Night vision is disrupted later, as rods are lost. Some of the genes associated with cone-rod dystrophy are also associated with other eye diseases, including a group of related eye disorders called rod-cone dystrophy. Rod-cone dystrophy has signs and symptoms similar to those of cone-rod dystrophy. However, rod-cone dystrophy is characterized by deterioration of the rods first, followed by the cones, so night vision is affected before daylight and color vision. The most common form of rod-cone dystrophy is a condition called retinitis pigmentosa. | cone-rod dystrophy |
Is cone-rod dystrophy inherited ? | Cone-rod dystrophy is usually inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. Less frequently, this condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most of these cases, an affected person has one parent with the condition. Rarely, cone-rod dystrophy is inherited in an X-linked recessive pattern. The genes associated with this form of the condition are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. Females with one copy of the altered gene have mild vision problems, such as decreased visual acuity. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | cone-rod dystrophy |
What are the treatments for cone-rod dystrophy ? | These resources address the diagnosis or management of cone-rod dystrophy: - Cleveland Clinic: Eye Examinations: What to Expect - Genetic Testing Registry: CONE-ROD DYSTROPHY, AIPL1-RELATED - Genetic Testing Registry: Cone-rod dystrophy - Genetic Testing Registry: Cone-rod dystrophy 1 - Genetic Testing Registry: Cone-rod dystrophy 10 - Genetic Testing Registry: Cone-rod dystrophy 11 - Genetic Testing Registry: Cone-rod dystrophy 12 - Genetic Testing Registry: Cone-rod dystrophy 13 - Genetic Testing Registry: Cone-rod dystrophy 15 - Genetic Testing Registry: Cone-rod dystrophy 16 - Genetic Testing Registry: Cone-rod dystrophy 17 - Genetic Testing Registry: Cone-rod dystrophy 18 - Genetic Testing Registry: Cone-rod dystrophy 19 - Genetic Testing Registry: Cone-rod dystrophy 2 - Genetic Testing Registry: Cone-rod dystrophy 20 - Genetic Testing Registry: Cone-rod dystrophy 21 - Genetic Testing Registry: Cone-rod dystrophy 3 - Genetic Testing Registry: Cone-rod dystrophy 5 - Genetic Testing Registry: Cone-rod dystrophy 6 - Genetic Testing Registry: Cone-rod dystrophy 7 - Genetic Testing Registry: Cone-rod dystrophy 8 - Genetic Testing Registry: Cone-rod dystrophy 9 - Genetic Testing Registry: Cone-rod dystrophy X-linked 3 - Genetic Testing Registry: Cone-rod dystrophy, X-linked 1 - MedlinePlus Encyclopedia: Color Vision Test - MedlinePlus Encyclopedia: Visual Acuity Test - MedlinePlus Encyclopedia: Visual Field Test These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | cone-rod dystrophy |
What is (are) 8p11 myeloproliferative syndrome ? | 8p11 myeloproliferative syndrome is a blood cancer that involves different types of blood cells. Blood cells are divided into several groups (lineages) based on the type of early cell from which they are descended. Two of these lineages are myeloid cells and lymphoid cells. Individuals with 8p11 myeloproliferative syndrome can develop both myeloid cell cancer and lymphoid cell cancer. The condition can occur at any age. It usually begins as a myeloproliferative disorder, which is characterized by a high number of white blood cells (leukocytes). Most affected individuals also have an excess of myeloid cells known as eosinophils (eosinophilia). In addition to a myeloproliferative disorder, many people with 8p11 myeloproliferative syndrome develop lymphoma, which is a form of blood cancer that involves lymphoid cells. The cancerous lymphoid cells grow and divide in lymph nodes, forming a tumor that enlarges the lymph nodes. In most cases of 8p11 myeloproliferative syndrome, the cancerous cells are lymphoid cells called T cells. Lymphoma can develop at the same time as the myeloproliferative disorder or later. In most people with 8p11 myeloproliferative syndrome, the myeloproliferative disorder develops into a fast-growing blood cancer called acute myeloid leukemia. The rapid myeloid and lymphoid cell production caused by these cancers results in enlargement of the spleen and liver (splenomegaly and hepatomegaly, respectively). Most people with 8p11 myeloproliferative syndrome have symptoms such as fatigue or night sweats. Some affected individuals have no symptoms, and the condition is discovered through routine blood tests. | 8p11 myeloproliferative syndrome |
How many people are affected by 8p11 myeloproliferative syndrome ? | The prevalence of 8p11 myeloproliferative syndrome is unknown. It is thought to be a rare condition. | 8p11 myeloproliferative syndrome |
What are the genetic changes related to 8p11 myeloproliferative syndrome ? | 8p11 myeloproliferative syndrome is caused by rearrangements of genetic material (translocations) between two chromosomes. All of the translocations that cause this condition involve the FGFR1 gene, which is found on the short (p) arm of chromosome 8 at a position described as p11. The translocations lead to fusion of part of the FGFR1 gene with part of another gene; the most common partner gene is ZMYM2 on chromosome 13. These genetic changes are found only in cancer cells. The protein normally produced from the FGFR1 gene can trigger a cascade of chemical reactions that instruct the cell to undergo certain changes, such as growing and dividing. This signaling is turned on when the FGFR1 protein interacts with growth factors. In contrast, when the FGFR1 gene is fused with another gene, FGFR1 signaling is turned on without the need for stimulation by growth factors. The uncontrolled signaling promotes continuous cell growth and division, leading to cancer. Researchers believe the mutations that cause this condition occur in a very early blood cell called a stem cell that has the ability to mature into either a myeloid cell or a lymphoid cell. For this reason, this condition is sometimes referred to as stem cell leukemia/lymphoma. | 8p11 myeloproliferative syndrome |
Is 8p11 myeloproliferative syndrome inherited ? | This condition is generally not inherited but arises from a mutation in the body's cells that occurs after conception. This alteration is called a somatic mutation. | 8p11 myeloproliferative syndrome |
What are the treatments for 8p11 myeloproliferative syndrome ? | These resources address the diagnosis or management of 8p11 myeloproliferative syndrome: - Cancer.Net from the American Society of Clinical Oncology: Acute Myeloid Leukemia Diagnosis - Cancer.Net from the American Society of Clinical Oncology: Acute Myeloid Leukemia Treatment Options - Cancer.Net from the American Society of Clinical Oncology: Non-Hodgkin Lymphoma Diagnosis - Cancer.Net from the American Society of Clinical Oncology: Non-Hodgkin Lymphoma Treatment Options - Genetic Testing Registry: Chromosome 8p11 myeloproliferative syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | 8p11 myeloproliferative syndrome |
What is (are) microcephaly-capillary malformation syndrome ? | Microcephaly-capillary malformation syndrome is an inherited disorder characterized by an abnormally small head size (microcephaly) and abnormalities of small blood vessels in the skin called capillaries (capillary malformations). In people with microcephaly-capillary malformation syndrome, microcephaly begins before birth and is associated with an unusually small brain and multiple brain abnormalities. Affected individuals develop seizures that can occur many times per day and are difficult to treat (intractable epilepsy). The problems with brain development and epilepsy lead to profound developmental delay and intellectual impairment. Most affected individuals do not develop skills beyond those of a 1- or 2-month-old infant. For example, most children with this condition are never able to control their head movements or sit unassisted. Capillary malformations are composed of enlarged capillaries that increase blood flow near the surface of the skin. These malformations look like pink or red spots on the skin. People with microcephaly-capillary malformation syndrome are born with anywhere from a few to hundreds of these spots, which can occur anywhere on the body. The spots are usually round or oval-shaped and range in size from the head of a pin to a large coin. Other signs and symptoms of microcephaly-capillary malformation syndrome include abnormal movements, feeding difficulties, slow growth, and short stature. Most affected individuals have abnormalities of the fingers and toes, including digits with tapered ends and abnormally small or missing fingernails and toenails. Some affected children also have distinctive facial features and an unusual pattern of hair growth on the scalp. | microcephaly-capillary malformation syndrome |
How many people are affected by microcephaly-capillary malformation syndrome ? | Microcephaly-capillary malformation syndrome is rare. About a dozen people have been diagnosed with the disorder. | microcephaly-capillary malformation syndrome |
What are the genetic changes related to microcephaly-capillary malformation syndrome ? | Microcephaly-capillary malformation syndrome results from mutations in the STAMBP gene. This gene provides instructions for making a protein called STAM binding protein. This protein plays a role in sorting damaged or unneeded proteins so they can be transported from the cell surface to specialized cell compartments that break down (degrade) or recycle them. This process helps to maintain the proper balance of protein production and breakdown (protein homeostasis) that cells need to function and survive. Studies suggest that STAM binding protein is also involved in multiple chemical signaling pathways within cells, including pathways needed for overall growth and the formation of new blood vessels (angiogenesis). Mutations in the STAMBP gene reduce or eliminate the production of STAM binding protein. This shortage allows damaged or unneeded proteins to build up inside cells instead of being degraded or recycled, which may damage cells and cause them to self-destruct (undergo apoptosis). Researchers suspect that abnormal apoptosis of brain cells starting before birth may cause microcephaly and the underlying brain abnormalities found in people with microcephaly-capillary malformation syndrome. A lack of STAM binding protein also alters multiple signaling pathways that are necessary for normal development, which may underlie the capillary malformations and other signs and symptoms of the condition. | microcephaly-capillary malformation syndrome |
Is microcephaly-capillary malformation syndrome inherited ? | This condition has an autosomal recessive pattern of inheritance, which means both copies of the STAMBP gene in each cell have mutations. An affected individual usually inherits one altered copy of the gene from each parent. Parents of an individual with an autosomal recessive condition typically do not show signs and symptoms of the condition. At least one individual with microcephaly-capillary malformation syndrome inherited two mutated copies of the STAMBP gene through a mechanism called uniparental isodisomy. In this case, an error occurred during the formation of egg or sperm cells, and the child received two copies of the mutated gene from one parent instead of one copy from each parent. | microcephaly-capillary malformation syndrome |
What are the treatments for microcephaly-capillary malformation syndrome ? | These resources address the diagnosis or management of microcephaly-capillary malformation syndrome: - Gene Review: Gene Review: Microcephaly-Capillary Malformation Syndrome - Genetic Testing Registry: Microcephaly-capillary malformation syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | microcephaly-capillary malformation syndrome |
What is (are) idiopathic inflammatory myopathy ? | Idiopathic inflammatory myopathy is a group of disorders characterized by inflammation of the muscles used for movement (skeletal muscles). Idiopathic inflammatory myopathy usually appears in adults between ages 40 and 60 or in children between ages 5 and 15, though it can occur at any age. The primary symptom of idiopathic inflammatory myopathy is muscle weakness, which develops gradually over a period of weeks to months or even years. Other symptoms include joint pain and general tiredness (fatigue). There are several forms of idiopathic inflammatory myopathy, including polymyositis, dermatomyositis, and sporadic inclusion body myositis. Polymyositis and dermatomyositis involve weakness of the muscles closest to the center of the body (proximal muscles), such as the muscles of the hips and thighs, upper arms, and neck. People with these forms of idiopathic inflammatory myopathy may find it difficult to climb stairs, get up from a seated position, or lift items above their head. In some cases, muscle weakness may make swallowing or breathing difficult. Polymyositis and dermatomyositis have similar symptoms, but dermatomyositis is distinguished by a reddish or purplish rash on the eyelids, elbows, knees, or knuckles. Sometimes, abnormal calcium deposits form hard, painful bumps under the skin (calcinosis). In sporadic inclusion body myositis, the muscles most affected are those of the wrists and fingers and the front of the thigh. Affected individuals may frequently stumble while walking and find it difficult to grasp items. As in dermatomyositis and polymyositis, swallowing can be difficult. | idiopathic inflammatory myopathy |
How many people are affected by idiopathic inflammatory myopathy ? | The incidence of idiopathic inflammatory myopathy is approximately 2 to 8 cases per million people each year. For unknown reasons, polymyositis and dermatomyositis are about twice as common in women as in men, while sporadic inclusion body myositis is more common in men. | idiopathic inflammatory myopathy |
What are the genetic changes related to idiopathic inflammatory myopathy ? | Idiopathic inflammatory myopathy is thought to arise from a combination of genetic and environmental factors. The term "idiopathic" indicates that the specific cause of the disorder is unknown. Researchers have identified variations in several genes that may influence the risk of developing idiopathic inflammatory myopathy. The most commonly associated genes belong to a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders (such as viruses and bacteria). Each HLA gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign proteins. Specific variations of several HLA genes seem to affect the risk of developing idiopathic inflammatory myopathy. Researchers are studying variations in other genes related to the body's immune function to understand how they contribute to the risk of developing idiopathic inflammatory myopathy. It is likely that specific genetic variations increase a person's risk of developing idiopathic inflammatory myopathy, and then exposure to certain environmental factors triggers the disorder. Infection, exposure to certain medications, and exposure to ultraviolet light (such as sunlight) have been identified as possible environmental triggers, but most risk factors for this condition remain unknown. | idiopathic inflammatory myopathy |
Is idiopathic inflammatory myopathy inherited ? | Most cases of idiopathic inflammatory myopathy are sporadic, which means they occur in people with no history of the disorder in their family. However, several people with idiopathic inflammatory myopathy have had close relatives with autoimmune disorders. Autoimmune diseases occur when the immune system malfunctions and attacks the body's tissues and organs. A small percentage of all cases of idiopathic inflammatory myopathy have been reported to run in families; however, the condition does not have a clear pattern of inheritance. Multiple genetic and environmental factors likely play a part in determining the risk of developing this disorder. As a result, inheriting a genetic variation linked with idiopathic inflammatory myopathy does not mean that a person will develop the condition. | idiopathic inflammatory myopathy |
What are the treatments for idiopathic inflammatory myopathy ? | These resources address the diagnosis or management of idiopathic inflammatory myopathy: - Genetic Testing Registry: Idiopathic myopathy - Genetic Testing Registry: Inclusion body myositis - Johns Hopkins Myositis Center: Diagnosis - Johns Hopkins Myositis Center: Treatment - Muscular Dystrophy Association: Facts about Inflammatory Myopathies (Myositis) These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | idiopathic inflammatory myopathy |
What is (are) bladder cancer ? | Bladder cancer is a disease in which certain cells in the bladder become abnormal and multiply without control or order. The bladder is a hollow, muscular organ in the lower abdomen that stores urine until it is ready to be excreted from the body. The most common type of bladder cancer begins in cells lining the inside of the bladder and is called transitional cell carcinoma (TCC). Bladder cancer may cause blood in the urine, pain during urination, frequent urination, or the feeling that one needs to urinate without results. These signs and symptoms are not specific to bladder cancer, however. They also can be caused by noncancerous conditions such as infections. | bladder cancer |
How many people are affected by bladder cancer ? | In the United States, bladder cancer is the fourth most common type of cancer in men and the ninth most common cancer in women. About 45,000 men and 17,000 women are diagnosed with bladder cancer each year. | bladder cancer |
What are the genetic changes related to bladder cancer ? | As with most cancers, the exact causes of bladder cancer are not known; however, many risk factors are associated with this disease. Many of the major risk factors are environmental, such as smoking and exposure to certain industrial chemicals. Studies suggest that chronic bladder inflammation, a parasitic infection called schistosomiasis, and some medications used to treat cancer are other environmental risk factors associated with bladder cancer. Genetic factors are also likely to play an important role in determining bladder cancer risk. Researchers have studied the effects of mutations in several genes, including FGFR3, RB1, HRAS, TP53, and TSC1, on the formation and growth of bladder tumors. Each of these genes plays a critical role in regulating cell division by preventing cells from dividing too rapidly or in an uncontrolled way. Alterations in these genes may help explain why some bladder cancers grow and spread more rapidly than others. Deletions of part or all of chromosome 9 are common events in bladder tumors. Researchers believe that several genes that control cell growth and division are probably located on chromosome 9. They are working to determine whether a loss of these genes plays a role in the development and progression of bladder cancer. Most of the genetic changes associated with bladder cancer develop in bladder tissue during a person's lifetime, rather than being inherited from a parent. Some people, however, appear to inherit a reduced ability to break down certain chemicals, which makes them more sensitive to the cancer-causing effects of tobacco smoke and industrial chemicals. | bladder cancer |
Is bladder cancer inherited ? | Bladder cancer is typically not inherited. Most often, tumors result from genetic mutations that occur in bladder cells during a person's lifetime. These noninherited genetic changes are called somatic mutations. | bladder cancer |
What are the treatments for bladder cancer ? | These resources address the diagnosis or management of bladder cancer: - Genetic Testing Registry: Malignant tumor of urinary bladder - MedlinePlus Encyclopedia: Bladder Cancer These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | bladder cancer |
What is (are) Langer-Giedion syndrome ? | Langer-Giedion syndrome is a condition that causes bone abnormalities and distinctive facial features. People with this condition have multiple noncancerous (benign) bone tumors called osteochondromas. Multiple osteochondromas may result in pain, limited range of joint movement, and pressure on nerves, blood vessels, the spinal cord, and tissues surrounding the osteochondromas. Affected individuals also have short stature and cone-shaped ends of the long bones (epiphyses). The characteristic appearance of individuals with Langer-Giedion syndrome includes sparse scalp hair, a rounded nose, a long flat area between the nose and the upper lip (philtrum), and a thin upper lip. Some people with this condition have loose skin in childhood, which typically resolves with age. Affected individuals may have some intellectual disability. | Langer-Giedion syndrome |
How many people are affected by Langer-Giedion syndrome ? | Langer-Giedion syndrome is a rare condition; its incidence is unknown. | Langer-Giedion syndrome |
What are the genetic changes related to Langer-Giedion syndrome ? | Langer-Giedion syndrome is caused by the deletion or mutation of at least two genes on chromosome 8. Researchers have determined that the loss of a functional EXT1 gene is responsible for the multiple osteochondromas seen in people with Langer-Giedion syndrome. Loss of a functional TRPS1 gene may cause the other bone and facial abnormalities. The EXT1 gene and the TRPS1 gene are always missing or mutated in affected individuals, but other neighboring genes may also be involved. The loss of additional genes from this region of chromosome 8 likely contributes to the varied features of this condition. Langer-Giedion syndrome is often described as a contiguous gene deletion syndrome because it results from the loss of several neighboring genes. | Langer-Giedion syndrome |
Is Langer-Giedion syndrome inherited ? | Most cases of Langer-Giedion syndrome are not inherited, but occur as random events during the formation of reproductive cells (eggs or sperm) in a parent of an affected individual. These cases occur in people with no history of the disorder in their family. There have been very few instances in which people with Langer-Giedion syndrome have inherited the chromosomal deletion from a parent with the condition. Langer-Giedion syndrome is considered an autosomal dominant condition because one copy of the altered chromosome 8 in each cell is sufficient to cause the disorder. | Langer-Giedion syndrome |
What are the treatments for Langer-Giedion syndrome ? | These resources address the diagnosis or management of Langer-Giedion syndrome: - Genetic Testing Registry: Langer-Giedion syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Langer-Giedion syndrome |
What is (are) FG syndrome ? | FG syndrome is a genetic condition that affects many parts of the body and occurs almost exclusively in males. "FG" represents the surname initials of the first family diagnosed with the disorder. FG syndrome affects intelligence and behavior. Almost everyone with the condition has intellectual disability, which ranges from mild to severe. Affected individuals tend to be friendly, inquisitive, and hyperactive, with a short attention span. Compared to people with other forms of intellectual disability, their socialization and daily living skills are strong, while verbal communication and language skills tend to be weaker. The physical features of FG syndrome include weak muscle tone (hypotonia), broad thumbs, and wide first (big) toes. Abnormalities of the tissue connecting the left and right halves of the brain (the corpus callosum) are also common. Most affected individuals have constipation, and many have abnormalities of the anus such as an obstruction of the anal opening (imperforate anus). People with FG syndrome also tend to have a distinctive facial appearance including small, underdeveloped ears; a tall, prominent forehead; and outside corners of the eyes that point downward (down-slanting palpebral fissures). Additional features seen in some people with FG syndrome include widely set eyes (hypertelorism), an upswept frontal hairline, and a large head compared to body size (relative macrocephaly). Other health problems have also been reported, including heart defects, seizures, undescended testes (cryptorchidism) in males, and a soft out-pouching in the lower abdomen (an inguinal hernia). | FG syndrome |
How many people are affected by FG syndrome ? | The prevalence of FG syndrome is unknown, although several hundred cases have been reported worldwide. Researchers suspect that FG syndrome may be overdiagnosed because many of its signs and symptoms are also seen with other disorders. | FG syndrome |
What are the genetic changes related to FG syndrome ? | Researchers have identified changes in five regions of the X chromosome that are linked to FG syndrome in affected families. Mutations in a gene called MED12, which is located in one of these regions, appear to be the most common cause of the disorder. Researchers are investigating genes in other regions of the X chromosome that may also be associated with FG syndrome. The MED12 gene provides instructions for making a protein that helps regulate gene activity. Specifically, the MED12 protein forms part of a large complex (a group of proteins that work together) that turns genes on and off. The MED12 protein is thought to play an essential role in development both before and after birth. At least two mutations in the MED12 gene have been found to cause FG syndrome. Although the mutations alter the structure of the MED12 protein, it is unclear how they lead to intellectual disability, behavioral changes, and the physical features associated with this condition. | FG syndrome |
Is FG syndrome inherited ? | FG syndrome is inherited in an X-linked recessive pattern. The genes likely associated with this disorder, including MED12, are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation usually must occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of a gene on the X chromosome, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | FG syndrome |
What are the treatments for FG syndrome ? | These resources address the diagnosis or management of FG syndrome: - Gene Review: Gene Review: MED12-Related Disorders - Genetic Testing Registry: FG syndrome - Genetic Testing Registry: FG syndrome 2 - Genetic Testing Registry: FG syndrome 3 - Genetic Testing Registry: FG syndrome 4 - Genetic Testing Registry: FG syndrome 5 - MedlinePlus Encyclopedia: Corpus Callosum of the Brain (image) - MedlinePlus Encyclopedia: Imperforate Anus These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | FG syndrome |
What is (are) Schwartz-Jampel syndrome ? | Schwartz-Jampel syndrome is a rare condition characterized by permanent muscle stiffness (myotonia) and bone abnormalities known as chondrodysplasia. The signs and symptoms of this condition become apparent sometime after birth, usually in early childhood. Either muscle stiffness or chondrodysplasia can appear first. The muscle and bone abnormalities worsen in childhood, although most affected individuals have a normal lifespan. The specific features of Schwartz-Jampel syndrome vary widely. Myotonia involves continuous tensing (contraction) of muscles used for movement (skeletal muscles) throughout the body. This sustained muscle contraction causes stiffness that interferes with eating, sitting, walking, and other movements. Sustained contraction of muscles in the face leads to a fixed, "mask-like" facial expression with narrow eye openings (blepharophimosis) and pursed lips. This facial appearance is very specific to Schwartz-Jampel syndrome. Affected individuals may also be nearsighted and experience abnormal blinking or spasms of the eyelids (blepharospasm). Chondrodysplasia affects the development of the skeleton, particularly the long bones in the arms and legs and the bones of the hips. These bones are shortened and unusually wide at the ends, so affected individuals have short stature. The long bones may also be abnormally curved (bowed). Other bone abnormalities associated with Schwartz-Jampel syndrome include a protruding chest (pectus carinatum), abnormal curvature of the spine, flattened bones of the spine (platyspondyly), and joint abnormalities called contractures that further restrict movement. Researchers originally described two types of Schwartz-Jampel syndrome. Type 1 has the signs and symptoms described above, while type 2 has more severe bone abnormalities and other health problems and is usually life-threatening in early infancy. Researchers have since discovered that the condition they thought was Schwartz-Jampel syndrome type 2 is actually part of another disorder, Stve-Wiedemann syndrome, which is caused by mutations in a different gene. They have recommended that the designation Schwartz-Jampel syndrome type 2 no longer be used. | Schwartz-Jampel syndrome |
How many people are affected by Schwartz-Jampel syndrome ? | Schwartz-Jampel syndrome appears to be a rare condition. About 150 cases have been reported in the medical literature. | Schwartz-Jampel syndrome |
What are the genetic changes related to Schwartz-Jampel syndrome ? | Schwartz-Jampel syndrome is caused by mutations in the HSPG2 gene. This gene provides instructions for making a protein known as perlecan. This protein is found in the extracellular matrix, which is the intricate lattice of proteins and other molecules that forms in the spaces between cells. Specifically, it is found in part of the extracellular matrix called the basement membrane, which is a thin, sheet-like structure that separates and supports cells in many tissues. Perlecan is also found in cartilage, a tough, flexible tissue that makes up much of the skeleton during early development. Most cartilage is later converted to bone, except for the cartilage that continues to cover and protect the ends of bones and is present in the nose and external ears. Perlecan has multiple functions, including cell signaling and the normal maintenance of basement membranes and cartilage. The protein also plays a critical role at the neuromuscular junction, which is the area between the ends of nerve cells and muscle cells where signals are relayed to trigger muscle contraction. The mutations that cause Schwartz-Jampel syndrome reduce the amount of perlecan that is produced or lead to a version of perlecan that is only partially functional. A reduction in the amount or function of this protein disrupts the normal development of cartilage and bone tissue, which underlies chondrodysplasia in affected individuals. A reduced amount of functional perlecan at the neuromuscular junction likely alters the balance of other molecules that signal when muscles should contract and when they should relax. As a result, muscle contraction is triggered continuously, leading to myotonia. | Schwartz-Jampel syndrome |
Is Schwartz-Jampel syndrome inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. | Schwartz-Jampel syndrome |
What are the treatments for Schwartz-Jampel syndrome ? | These resources address the diagnosis or management of Schwartz-Jampel syndrome: - Genetic Testing Registry: Schwartz Jampel syndrome type 1 - National Institute of Neurological Disorders and Stroke: Myotonia Information Page These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Schwartz-Jampel syndrome |
What is (are) Asperger syndrome ? | Asperger syndrome is a disorder on the autism spectrum, which is a group of conditions characterized by impaired communication and social interaction. Asperger syndrome is on the mild, or "high-functioning," end of the autism spectrum. Many affected individuals learn to compensate for their differences and live independent and successful lives. However, the behavioral challenges associated with this condition often lead to social isolation and difficulties at school, at work, and in personal relationships. People with Asperger syndrome have average or above-average intelligence. In contrast to people with other disorders on the autism spectrum, they are not delayed in their language development. However, their ability to carry on a conversation is often impaired by a tendency to take idioms or humorous statements literally and an inability to read non-verbal cues such as body language to understand what others are feeling. They may speak in a monotone voice, have unusual mannerisms, or choose unusual topics of conversation. Individuals with Asperger syndrome tend to develop an intense interest in a particular subject. This interest may be a traditional hobby or academic discipline, and many people with Asperger syndrome develop advanced abilities in fields such as music, science, mathematics, or computer programming. However, they might also focus on an unusual interest such as bus routes or a particular type of household appliance. Often they are able to remember enormous amounts of detail on their subject of interest. They may want to share this large amount of information with others and may resist diversion to other topics. People with Asperger syndrome tend to be rigid about their established routines and may strongly resist disruptions such as changes in schedule. They may also have difficulty tolerating sensory stimuli such as noise or lights. Other features of Asperger syndrome may include mild impairment of motor skills. For example, basic skills such as crawling and walking may be somewhat delayed. Affected individuals may also have coordination problems that impair their ability to engage in such activities as playing ball games or riding a bicycle. This physical clumsiness may lead to further social isolation of children with Asperger syndrome. Signs and symptoms of Asperger syndrome may become apparent by the age of 3, when most children begin to develop social skills such as learning to play with others. Some affected children may come to medical attention due to delayed motor skills. In most cases, children with Asperger syndrome are diagnosed during the elementary school years, as their social behavior continues to diverge from the typical developmental path. Difficulties with social skills generally continue into adulthood, and affected individuals are at increased risk of other behavioral or psychiatric disorders such as attention deficit-hyperactivity disorder (ADHD), depression, anxiety, and obsessive-compulsive disorder. | Asperger syndrome |
How many people are affected by Asperger syndrome ? | The prevalence of Asperger syndrome is not well established. Estimates range from 1 in 250 to 1 in 5,000 children. Three to four times as many males are affected than females. Because of changes in the way developmental disorders are classified, Asperger syndrome was not often diagnosed in adults until recently, and the prevalence is often perceived to be rising as more people are recognized to have features of the condition. Many mildly affected individuals likely continue to be undiagnosed. | Asperger syndrome |
What are the genetic changes related to Asperger syndrome ? | While genetic factors are believed to contribute to the development of Asperger syndrome, no related genes have been confirmed. It is unclear whether certain gene variations that are being studied in other autism spectrum disorders will play a role in Asperger syndrome. It appears likely that a combination of genetic variations and environmental factors influence the development of this complex condition. Asperger syndrome is a disorder of brain development. Researchers have identified differences in the structure and function of specific regions of the brain between children with Asperger syndrome and unaffected children. These differences likely arise during development before birth, when cells in the brain are migrating to their proper places. The differences in brain development that occur in Asperger syndrome appear to affect areas of the brain involved in thought, behavior, and emotions, such as the prefrontal cortex, the amygdala, and the fusiform face area. In particular, cognitive functions called theory of mind, central coherence, and executive function are affected. Theory of mind is the ability to understand that other people have their own ideas, emotions, and perceptions, and to empathize with them. It is related to the proper functioning of a brain mechanism called the mirror neuron system, which is normally active both when certain actions are performed and when others are observed performing the same actions. Researchers believe that the mirror neuron system is impaired in people with Asperger syndrome. Central coherence is the ability to integrate individual perceptions into a larger context, commonly known as "seeing the big picture." For example, a person with Asperger syndrome may be able to describe individual trees in great detail without recognizing that they are part of a forest. Executive function is the ability to plan and implement actions and develop problem-solving strategies. This function includes skills such as impulse control, self-monitoring, focusing attention appropriately, and cognitive flexibility. People with deficits in these skills may have difficulty in some activities of daily living and in social interactions. The differences in cognitive functioning observed in people with Asperger syndrome are believed to give rise to the behavioral patterns characteristic of this condition. | Asperger syndrome |
Is Asperger syndrome inherited ? | Autism spectrum disorders including Asperger syndrome have a tendency to run in families, but the inheritance pattern is unknown. | Asperger syndrome |
What are the treatments for Asperger syndrome ? | These resources address the diagnosis or management of Asperger syndrome: - Genetic Testing Registry: Asperger syndrome 1 - Genetic Testing Registry: Asperger syndrome 2 - Genetic Testing Registry: Asperger syndrome 3 - Genetic Testing Registry: Asperger syndrome 4 - Genetic Testing Registry: Asperger syndrome X-linked 1 - Genetic Testing Registry: Asperger syndrome X-linked 2 - Genetic Testing Registry: Asperger's disorder - MedlinePlus Encyclopedia: Asperger Syndrome - National Institute of Mental Health: How is ASD treated? These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Asperger syndrome |
What is (are) mucopolysaccharidosis type IV ? | Mucopolysaccharidosis type IV (MPS IV), also known as Morquio syndrome, is a progressive condition that mainly affects the skeleton. The rate at which symptoms worsen varies among affected individuals. The first signs and symptoms of MPS IV usually become apparent during early childhood. Affected individuals develop various skeletal abnormalities, including short stature, knock knees, and abnormalities of the ribs, chest, spine, hips, and wrists. People with MPS IV often have joints that are loose and very flexible (hypermobile), but they may also have restricted movement in certain joints. A characteristic feature of this condition is underdevelopment (hypoplasia) of a peg-like bone in the neck called the odontoid process. The odontoid process helps stabilize the spinal bones in the neck (cervical vertebrae). Odontoid hypoplasia can lead to misalignment of the cervical vertebrae, which may compress and damage the spinal cord, resulting in paralysis or death. In people with MPS IV, the clear covering of the eye (cornea) typically becomes cloudy, which can cause vision loss. Some affected individuals have recurrent ear infections and hearing loss. The airway may become narrow in some people with MPS IV, leading to frequent upper respiratory infections and short pauses in breathing during sleep (sleep apnea). Other common features of this condition include mildly "coarse" facial features, thin tooth enamel, multiple cavities, heart valve abnormalities, a mildly enlarged liver (hepatomegaly), and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia). Unlike some other types of mucopolysaccharidosis, MPS IV does not affect intelligence. The life expectancy of individuals with MPS IV depends on the severity of symptoms. Severely affected individuals may survive only until late childhood or adolescence. Those with milder forms of the disorder usually live into adulthood, although their life expectancy may be reduced. Spinal cord compression and airway obstruction are major causes of death in people with MPS IV. | mucopolysaccharidosis type IV |
How many people are affected by mucopolysaccharidosis type IV ? | The exact prevalence of MPS IV is unknown, although it is estimated to occur in 1 in 200,000 to 300,000 individuals. | mucopolysaccharidosis type IV |
What are the genetic changes related to mucopolysaccharidosis type IV ? | Mutations in the GALNS and GLB1 genes cause MPS IV. These genes provide instructions for producing enzymes involved in the breakdown of large sugar molecules called glycosaminoglycans (GAGs). GAGs were originally called mucopolysaccharides, which is where this condition gets its name. When MPS IV is caused by mutations in the GALNS gene it is called MPS IV type A (MPS IVA), and when it is caused by mutations in the GLB1 gene it is called MPS IV type B (MPS IVB). In general, the two types of MPS IV cannot be distinguished by their signs and symptoms. Mutations in the GALNS and GLB1 genes reduce or completely eliminate the activity of the enzymes produced from these genes. Without these enzymes, GAGs accumulate within cells, specifically inside the lysosomes. Lysosomes are compartments in the cell that break down and recycle different types of molecules. Conditions such as MPS IV that cause molecules to build up inside the lysosomes are called lysosomal storage disorders. In MPS IV, GAGs accumulate to toxic levels in many tissues and organs, particularly in the bones. The accumulation of GAGs causes the bone deformities in this disorder. Researchers believe that the buildup of GAGs may also cause the features of MPS IV by interfering with the functions of other proteins inside lysosomes and disrupting the movement of molecules inside the cell. | mucopolysaccharidosis type IV |
Is mucopolysaccharidosis type IV inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. | mucopolysaccharidosis type IV |
What are the treatments for mucopolysaccharidosis type IV ? | These resources address the diagnosis or management of mucopolysaccharidosis type IV: - Genetic Testing Registry: Morquio syndrome - Genetic Testing Registry: Mucopolysaccharidosis, MPS-IV-A - Genetic Testing Registry: Mucopolysaccharidosis, MPS-IV-B - MedlinePlus Encyclopedia: Morquio syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | mucopolysaccharidosis type IV |
What is (are) juvenile primary lateral sclerosis ? | Juvenile primary lateral sclerosis is a rare disorder characterized by progressive weakness and tightness (spasticity) of muscles in the arms, legs, and face. The features of this disorder are caused by damage to motor neurons, which are specialized nerve cells in the brain and spinal cord that control muscle movement. Symptoms of juvenile primary lateral sclerosis begin in early childhood and progress slowly over many years. Early symptoms include clumsiness, muscle weakness and spasticity in the legs, and difficulty with balance. As symptoms progress, the spasticity spreads to the arms and hands and individuals develop slurred speech, drooling, difficulty swallowing, and an inability to walk. | juvenile primary lateral sclerosis |
How many people are affected by juvenile primary lateral sclerosis ? | Juvenile primary lateral sclerosis is a rare disorder, with few reported cases. | juvenile primary lateral sclerosis |
What are the genetic changes related to juvenile primary lateral sclerosis ? | Mutations in the ALS2 gene cause most cases of juvenile primary lateral sclerosis. This gene provides instructions for making a protein called alsin. Alsin is abundant in motor neurons, but its function is not fully understood. Mutations in the ALS2 gene alter the instructions for producing alsin. As a result, alsin is unstable and is quickly broken down, or it cannot function properly. It is unclear how the loss of functional alsin protein damages motor neurons and causes juvenile primary lateral sclerosis. | juvenile primary lateral sclerosis |
Is juvenile primary lateral sclerosis inherited ? | When caused by mutations in the ALS2 gene, juvenile primary lateral sclerosis is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. | juvenile primary lateral sclerosis |
What are the treatments for juvenile primary lateral sclerosis ? | These resources address the diagnosis or management of juvenile primary lateral sclerosis: - Gene Review: Gene Review: ALS2-Related Disorders - Genetic Testing Registry: Juvenile primary lateral sclerosis These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | juvenile primary lateral sclerosis |
What is (are) spinal muscular atrophy ? | Spinal muscular atrophy is a genetic disorder that affects the control of muscle movement. It is caused by a loss of specialized nerve cells, called motor neurons, in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). The loss of motor neurons leads to weakness and wasting (atrophy) of muscles used for activities such as crawling, walking, sitting up, and controlling head movement. In severe cases of spinal muscular atrophy, the muscles used for breathing and swallowing are affected. There are many types of spinal muscular atrophy distinguished by the pattern of features, severity of muscle weakness, and age when the muscle problems begin. Type I spinal muscular atrophy (also called Werdnig-Hoffman disease) is a severe form of the disorder that is evident at birth or within the first few months of life. Affected infants are developmentally delayed; most are unable to support their head or sit unassisted. Children with this type have breathing and swallowing problems that may lead to choking or gagging. Type II spinal muscular atrophy is characterized by muscle weakness that develops in children between ages 6 and 12 months. Children with type II can sit without support, although they may need help getting to a seated position. Individuals with this type of spinal muscular atrophy cannot stand or walk unaided. Type III spinal muscular atrophy (also called Kugelberg-Welander disease or juvenile type) has milder features that typically develop between early childhood and adolescence. Individuals with type III spinal muscular atrophy can stand and walk unaided, but walking and climbing stairs may become increasingly difficult. Many affected individuals will require wheelchair assistance later in life. The signs and symptoms of type IV spinal muscular atrophy often occur after age 30. Affected individuals usually experience mild to moderate muscle weakness, tremor, twitching, or mild breathing problems. Typically, only muscles close to the center of the body (proximal muscles), such as the upper arms and legs, are affected in type IV spinal muscular atrophy. The features of X-linked spinal muscular atrophy appear in infancy and include severe muscle weakness and difficulty breathing. Children with this type often have joint deformities (contractures) that impair movement. In severe cases, affected infants are born with broken bones. Poor muscle tone before birth may contribute to the contractures and broken bones seen in these children. Spinal muscular atrophy, lower extremity, dominant (SMA-LED) is characterized by leg muscle weakness that is most severe in the thigh muscles (quadriceps). This weakness begins in infancy or early childhood and progresses slowly. Affected individuals often have a waddling or unsteady walk and have difficulty rising from a seated position and climbing stairs. An adult-onset form of spinal muscular atrophy that begins in early to mid-adulthood affects the proximal muscles and is characterized by muscle cramping of the limbs and abdomen, weakness in the leg muscles, involuntary muscle contractions, tremors, and a protrusion of the abdomen thought to be related to muscle weakness. Some affected individuals experience difficulty swallowing and problems with bladder and bowel function. | spinal muscular atrophy |
How many people are affected by spinal muscular atrophy ? | Spinal muscular atrophy affects 1 in 6,000 to 1 in 10,000 people. | spinal muscular atrophy |
What are the genetic changes related to spinal muscular atrophy ? | Mutations in the SMN1, UBA1, DYNC1H1, and VAPB genes cause spinal muscular atrophy. Extra copies of the SMN2 gene modify the severity of spinal muscular atrophy. The SMN1 and SMN2 genes provide instructions for making a protein called the survival motor neuron (SMN) protein. The SMN protein is important for the maintenance of specialized nerve cells called motor neurons. Motor neurons are located in the spinal cord and the brainstem; they control muscle movement. Most functional SMN protein is produced from the SMN1 gene, with a small amount produced from the SMN2 gene. Several different versions of the SMN protein are produced from the SMN2 gene, but only one version is full size and functional. Mutations in the SMN1 gene cause spinal muscular atrophy types I, II, III, and IV. SMN1 gene mutations lead to a shortage of the SMN protein. Without SMN protein, motor neurons die, and nerve impulses are not passed between the brain and muscles. As a result, some muscles cannot perform their normal functions, leading to weakness and impaired movement. Some people with type II, III, or IV spinal muscular atrophy have three or more copies of the SMN2 gene in each cell. Having multiple copies of the SMN2 gene can modify the course of spinal muscular atrophy. The additional SMN proteins produced from the extra copies of the SMN2 gene can help replace some of the SMN protein that is lost due to mutations in the SMN1 gene. In general, symptoms are less severe and begin later in life as the number of copies of the SMN2 gene increases. Mutations in the UBA1 gene cause X-linked spinal muscular atrophy. The UBA1 gene provides instructions for making the ubiquitin-activating enzyme E1. This enzyme is involved in a process that targets proteins to be broken down (degraded) within cells. UBA1 gene mutations lead to reduced or absent levels of functional enzyme, which disrupts the process of protein degradation. A buildup of proteins in the cell can cause it to die; motor neurons are particularly susceptible to damage from protein buildup. The DYNC1H1 gene provides instructions for making a protein that is part of a group (complex) of proteins called dynein. This complex is found in the fluid inside cells (cytoplasm), where it is part of a network that moves proteins and other materials. In neurons, dynein moves cellular materials away from the junctions between neurons (synapses) to the center of the cell. This process helps transmit chemical messages from one neuron to another. DYNC1H1 gene mutations that cause SMA-LED disrupt the function of the dynein complex. As a result, the movement of proteins, cellular structures, and other materials within cells are impaired. A decrease in chemical messaging between neurons that control muscle movement is thought to contribute to the muscle weakness experienced by people with SMA-LED. It is unclear why this condition affects only the lower extremities. The adult-onset form of spinal muscular atrophy is caused by a mutation in the VAPB gene. The VAPB gene provides instructions for making a protein that is found in cells throughout the body. Researchers suggest that this protein may play a role in preventing the buildup of unfolded or misfolded proteins within cells. It is unclear how a VAPB gene mutation leads to the loss of motor neurons. An impaired VAPB protein might cause misfolded and unfolded proteins to accumulate and impair the normal function of motor neurons. Other types of spinal muscular atrophy that primarily affect the lower legs and feet and the lower arms and hands are caused by the dysfunction of neurons in the spinal cord. When spinal muscular atrophy shows this pattern of signs and symptoms, it is also known as distal hereditary motor neuropathy. The various types of this condition are caused by mutations in other genes. | spinal muscular atrophy |
Is spinal muscular atrophy inherited ? | Types I, II, III, and IV spinal muscular atrophy are inherited in an autosomal recessive pattern, which means both copies of the SMN1 gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. Extra copies of the SMN2 gene are due to a random error when making new copies of DNA (replication) in an egg or sperm cell or just after fertilization. SMA-LED and the late-onset form of spinal muscular atrophy caused by VAPB gene mutations are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. X-linked spinal muscular atrophy is inherited in an X-linked pattern. The UBA1 gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | spinal muscular atrophy |
What are the treatments for spinal muscular atrophy ? | These resources address the diagnosis or management of spinal muscular atrophy: - Gene Review: Gene Review: Spinal Muscular Atrophy - Gene Review: Gene Review: Spinal Muscular Atrophy, X-Linked Infantile - Genetic Testing Registry: Adult proximal spinal muscular atrophy, autosomal dominant - Genetic Testing Registry: Arthrogryposis multiplex congenita, distal, X-linked - Genetic Testing Registry: Kugelberg-Welander disease - Genetic Testing Registry: Spinal muscular atrophy type 4 - Genetic Testing Registry: Spinal muscular atrophy, lower extremity predominant 1, autosomal dominant - Genetic Testing Registry: Spinal muscular atrophy, type II - Genetic Testing Registry: Werdnig-Hoffmann disease - Genomics Education Programme (UK) - MedlinePlus Encyclopedia: Spinal Muscular Atrophy These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | spinal muscular atrophy |
What is (are) hereditary diffuse gastric cancer ? | Hereditary diffuse gastric cancer (HDGC) is an inherited disorder that greatly increases the chance of developing a form of stomach (gastric) cancer. In this form, known as diffuse gastric cancer, there is no solid tumor. Instead cancerous (malignant) cells multiply underneath the stomach lining, making the lining thick and rigid. The invasive nature of this type of cancer makes it highly likely that these cancer cells will spread (metastasize) to other tissues, such as the liver or nearby bones. Symptoms of diffuse gastric cancer occur late in the disease and can include stomach pain, nausea, vomiting, difficulty swallowing (dysphagia), decreased appetite, and weight loss. If the cancer metastasizes to other tissues, it may lead to an enlarged liver, yellowing of the eyes and skin (jaundice), an abnormal buildup of fluid in the abdominal cavity (ascites), firm lumps under the skin, or broken bones. In HDGC, gastric cancer usually occurs in a person's late thirties or early forties, although it can develop anytime during adulthood. If diffuse gastric cancer is detected early, the survival rate is high; however, because this type of cancer is hidden underneath the stomach lining, it is usually not diagnosed until the cancer has become widely invasive. At that stage of the disease, the survival rate is approximately 20 percent. Some people with HDGC have an increased risk of developing other types of cancer, such as a form of breast cancer in women that begins in the milk-producing glands (lobular breast cancer); prostate cancer; and cancers of the colon (large intestine) and rectum, which are collectively referred to as colorectal cancer. Most people with HDGC have family members who have had one of the types of cancer associated with HDGC. In some families, all the affected members have diffuse gastric cancer. In other families, some affected members have diffuse gastric cancer and others have another associated form of cancer, such as lobular breast cancer. Frequently, HDGC-related cancers develop in individuals before the age of 50. | hereditary diffuse gastric cancer |
How many people are affected by hereditary diffuse gastric cancer ? | Gastric cancer is the fourth most common form of cancer worldwide, affecting 900,000 people per year. HDGC probably accounts for less than 1 percent of these cases. | hereditary diffuse gastric cancer |
What are the genetic changes related to hereditary diffuse gastric cancer ? | It is likely that 30 to 40 percent of individuals with HDGC have a mutation in the CDH1 gene. The CDH1 gene provides instructions for making a protein called epithelial cadherin or E-cadherin. This protein is found within the membrane that surrounds epithelial cells, which are the cells that line the surfaces and cavities of the body. E-cadherin helps neighboring cells stick to one another (cell adhesion) to form organized tissues. E-cadherin has many other functions including acting as a tumor suppressor protein, which means it prevents cells from growing and dividing too rapidly or in an uncontrolled way. People with HDGC caused by CDH1 gene mutations are born with one mutated copy of the gene in each cell. These mutations cause the production of an abnormally short, nonfunctional version of E-cadherin or alter the protein's structure. For diffuse gastric cancer to develop, a second mutation involving the other copy of the CDH1 gene must occur in the cells of the stomach lining during a person's lifetime. People who are born with one mutated copy of the CDH1 gene have a 80 percent chance of acquiring a second mutation in the other copy of the gene and developing gastric cancer in their lifetimes. When both copies of the CDH1 gene are mutated in a particular cell, that cell cannot produce any functional E-cadherin. The loss of this protein prevents it from acting as a tumor suppressor, contributing to the uncontrollable growth and division of cells. A lack of E-cadherin also impairs cell adhesion, increasing the likelihood that cancer cells will not come together to form a tumor but will invade the stomach wall and metastasize as small clusters of cancer cells into nearby tissues. These CDH1 gene mutations also lead to a 40 to 50 percent chance of lobular breast cancer in women, a slightly increased risk of prostate cancer in men, and a slightly increased risk of colorectal cancer. It is unclear why CDH1 gene mutations primarily occur in the stomach lining and these other tissues. About 60 to 70 percent of individuals with HDGC do not have an identified mutation in the CDH1 gene. The cancer-causing mechanism in these individuals is unknown. | hereditary diffuse gastric cancer |
Is hereditary diffuse gastric cancer inherited ? | HDGC is inherited in an autosomal dominant pattern, which means one copy of the altered CDH1 gene in each cell is sufficient to increase the risk of developing cancer. In most cases, an affected person has one parent with the condition. | hereditary diffuse gastric cancer |
What are the treatments for hereditary diffuse gastric cancer ? | These resources address the diagnosis or management of hereditary diffuse gastric cancer: - American Cancer Society: How is Stomach Cancer Diagnosed? - Gene Review: Gene Review: Hereditary Diffuse Gastric Cancer - Genetic Testing Registry: Hereditary diffuse gastric cancer - MedlinePlus Encyclopedia: Gastric Cancer - Memorial Sloan-Kettering Cancer Center: Early Onset and Familial Gastric Cancer Registry - National Cancer Institute: Gastric Cancer Treatment Option Overview These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | hereditary diffuse gastric cancer |
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