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What is (are) X-linked infantile spasm syndrome ? | X-linked infantile spasm syndrome is a seizure disorder characterized by a type of seizure known as infantile spasms. The spasms usually appear before the age of 1. Several types of spasms have been described, but the most commonly reported involves bending at the waist and neck with extension of the arms and legs (sometimes called a jackknife spasm). Each spasm lasts only seconds, but they occur in clusters several minutes long. Although individuals are not usually affected while they are sleeping, the spasms commonly occur just after awakening. Infantile spasms usually disappear by age 5, but many children then develop other types of seizures that recur throughout their lives. Most babies with X-linked infantile spasm syndrome have characteristic results on an electroencephalogram (EEG), a test used to measure the electrical activity of the brain. The EEG of these individuals typically shows an irregular pattern known as hypsarrhythmia, and this finding can help differentiate infantile spasms from other types of seizures. Because of the recurrent seizures, babies with X-linked infantile spasm syndrome stop developing normally and begin to lose skills they have acquired (developmental regression), such as sitting, rolling over, and babbling. Subsequently, development in affected children is delayed. Most affected individuals also have intellectual disability throughout their lives. | X-linked infantile spasm syndrome |
How many people are affected by X-linked infantile spasm syndrome ? | Infantile spasms are estimated to affect 1 to 1.6 in 100,000 individuals. This estimate includes X-linked infantile spasm syndrome as well as infantile spasms that have other causes. | X-linked infantile spasm syndrome |
What are the genetic changes related to X-linked infantile spasm syndrome ? | X-linked infantile spasm syndrome is caused by mutations in either the ARX gene or the CDKL5 gene. The proteins produced from these genes play a role in the normal functioning of the brain. The ARX protein is involved in the regulation of other genes that contribute to brain development. The CDKL5 protein is thought to regulate the activity of at least one protein that is critical for normal brain function. Researchers are working to determine how mutations in either of these genes lead to seizures and intellectual disability. Infantile spasms can have nongenetic causes, such as brain malformations, other disorders that affect brain function, or brain damage. In addition, changes in genes that are not located on the X chromosome cause infantile spasms in rare cases. | X-linked infantile spasm syndrome |
Is X-linked infantile spasm syndrome inherited ? | X-linked infantile spasm syndrome can have different inheritance patterns depending on the genetic cause. When caused by mutations in the ARX gene, this condition is inherited in an X-linked recessive pattern. The ARX 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. Usually in females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. However, in some instances, one altered copy of the ARX gene is sufficient because the X chromosome with the normal copy of the ARX gene is turned off through a process called X-inactivation. Early in embryonic development in females, one of the two X chromosomes is permanently inactivated in somatic cells (cells other than egg and sperm cells). X-inactivation ensures that females, like males, have only one active copy of the X chromosome in each body cell. Usually X-inactivation occurs randomly, such that each X chromosome is active in about half of the body cells. Sometimes X-inactivation is not random, and one X chromosome is active in more than half of cells. When X-inactivation does not occur randomly, it is called skewed X-inactivation. Some ARX gene mutations may be associated with skewed X-inactivation, which results in the inactivation of the X chromosome with the normal copy of the ARX gene in most cells of the body. This skewed X-inactivation causes the chromosome with the mutated ARX gene to be expressed in more than half of cells, causing X-linked infantile spasm syndrome. When caused by mutations in the CDKL5 gene, this condition is thought to have an X-linked dominant inheritance pattern. The CDKL5 gene is also located on the X chromosome, making this condition X-linked. The inheritance is dominant because one copy of the altered gene in each cell is sufficient to cause the condition in both males and females. X-linked infantile spasm syndrome caused by CDKL5 gene mutations usually occurs in individuals with no history of the disorder in their family. These mutations likely occur in early embryonic development (called de novo mutations). Because males have only one X chromosome, X-linked dominant disorders are often more severe in males than in females. Male fetuses with CDKL5-related X-linked infantile spasm syndrome may not survive to birth, so more females are diagnosed with the condition. In females, the distribution of active and inactive X chromosomes due to X-inactivation may affect whether a woman develops the condition or the severity of the signs and symptoms. Generally, the larger the proportion of active X chromosomes that contain the mutated CDKL5 gene, the more severe the signs and symptoms of the condition are. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | X-linked infantile spasm syndrome |
What are the treatments for X-linked infantile spasm syndrome ? | These resources address the diagnosis or management of X-linked infantile spasm syndrome: - Child Neurology Foundation - Genetic Testing Registry: Early infantile epileptic encephalopathy 2 - Genetic Testing Registry: West 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 | X-linked infantile spasm syndrome |
What is (are) tetra-amelia syndrome ? | Tetra-amelia syndrome is a very rare disorder characterized by the absence of all four limbs. ("Tetra" is the Greek word for "four," and "amelia" refers to the failure of an arm or leg to develop before birth.) This syndrome can also cause severe malformations of other parts of the body, including the face and head, heart, nervous system, skeleton, and genitalia. The lungs are underdeveloped in many cases, which makes breathing difficult or impossible. Because children with tetra-amelia syndrome have such serious medical problems, most are stillborn or die shortly after birth. | tetra-amelia syndrome |
How many people are affected by tetra-amelia syndrome ? | Tetra-amelia syndrome has been reported in only a few families worldwide. | tetra-amelia syndrome |
What are the genetic changes related to tetra-amelia syndrome ? | Researchers have found a mutation in the WNT3 gene in people with tetra-amelia syndrome from one large family. This gene is part of a family of WNT genes that play critical roles in development before birth. The protein produced from the WNT3 gene is involved in the formation of the limbs and other body systems during embryonic development. Mutations in the WNT3 gene prevent cells from producing functional WNT3 protein, which disrupts normal limb formation and leads to the other serious birth defects associated with tetra-amelia syndrome. In other affected families, the cause of tetra-amelia syndrome has not been determined. Researchers believe that unidentified mutations in WNT3 or other genes involved in limb development are probably responsible for the disorder in these cases. | tetra-amelia syndrome |
Is tetra-amelia syndrome inherited ? | In most of the families reported so far, tetra-amelia syndrome appears to have an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means both copies of the gene in each cell have mutations. The parents of an individual with tetra-amelia syndrome each carry one copy of the mutated gene, but do not show signs and symptoms of the condition. | tetra-amelia syndrome |
What are the treatments for tetra-amelia syndrome ? | These resources address the diagnosis or management of tetra-amelia syndrome: - Gene Review: Gene Review: Tetra-Amelia Syndrome - Genetic Testing Registry: Tetraamelia, autosomal recessive 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 | tetra-amelia syndrome |
What is (are) X-linked creatine deficiency ? | X-linked creatine deficiency is an inherited disorder that primarily affects the brain. People with this disorder have intellectual disability, which can range from mild to severe, and delayed speech development. Some affected individuals develop behavioral disorders such as attention deficit hyperactivity disorder or autistic behaviors that affect communication and social interaction. They may also experience seizures. Children with X-linked creatine deficiency may experience slow growth and exhibit delayed development of motor skills such as sitting and walking. Affected individuals tend to tire easily. A small number of people with X-linked creatine deficiency have additional signs and symptoms including abnormal heart rhythms, an unusually small head (microcephaly), or distinctive facial features such as a broad forehead and a flat or sunken appearance of the middle of the face (midface hypoplasia). | X-linked creatine deficiency |
How many people are affected by X-linked creatine deficiency ? | The prevalence of X-linked creatine deficiency is unknown. More than 150 affected individuals have been identified. The disorder has been estimated to account for between 1 and 2 percent of males with intellectual disability. | X-linked creatine deficiency |
What are the genetic changes related to X-linked creatine deficiency ? | Mutations in the SLC6A8 gene cause X-linked creatine deficiency. The SLC6A8 gene provides instructions for making a protein that transports the compound creatine into cells. Creatine is needed for the body to store and use energy properly. SLC6A8 gene mutations impair the ability of the transporter protein to bring creatine into cells, resulting in a creatine shortage (deficiency). The effects of creatine deficiency are most severe in organs and tissues that require large amounts of energy, especially the brain. | X-linked creatine deficiency |
Is X-linked creatine deficiency inherited ? | This condition is inherited in an X-linked pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In females (who have two X chromosomes), a mutation in one of the two copies of the gene in each cell may or may not cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of the gene in each cell causes the disorder. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. In most cases of X-linked inheritance, males experience more severe symptoms of the disorder than females. About half of females with one mutated copy of the SLC6A8 gene in each cell have intellectual disability, learning difficulties, or behavioral problems. Other females with one mutated copy of the SLC6A8 gene in each cell have no noticeable neurological problems. | X-linked creatine deficiency |
What are the treatments for X-linked creatine deficiency ? | These resources address the diagnosis or management of X-linked creatine deficiency: - Gene Review: Gene Review: Creatine Deficiency Syndromes - Genetic Testing Registry: Creatine deficiency, X-linked 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 | X-linked creatine deficiency |
What is (are) Schindler disease ? | Schindler disease is an inherited disorder that primarily causes neurological problems. There are three types of Schindler disease. Schindler disease type I, also called the infantile type, is the most severe form. Babies with Schindler disease type I appear healthy at birth, but by the age of 8 to 15 months they stop developing new skills and begin losing skills they had already acquired (developmental regression). As the disorder progresses, affected individuals develop blindness and seizures, and eventually they lose awareness of their surroundings and become unresponsive. People with this form of the disorder usually do not survive past early childhood. Schindler disease type II, also called Kanzaki disease, is a milder form of the disorder that usually appears in adulthood. Affected individuals may develop mild cognitive impairment and hearing loss caused by abnormalities of the inner ear (sensorineural hearing loss). They may experience weakness and loss of sensation due to problems with the nerves connecting the brain and spinal cord to muscles and sensory cells (peripheral nervous system). Clusters of enlarged blood vessels that form small, dark red spots on the skin (angiokeratomas) are characteristic of this form of the disorder. Schindler disease type III is intermediate in severity between types I and II. Affected individuals may exhibit signs and symptoms beginning in infancy, including developmental delay, seizures, a weakened and enlarged heart (cardiomyopathy), and an enlarged liver (hepatomegaly). In other cases, people with this form of the disorder exhibit behavioral problems beginning in early childhood, with some features of autism spectrum disorders. Autism spectrum disorders are characterized by impaired communication and socialization skills. | Schindler disease |
How many people are affected by Schindler disease ? | Schindler disease is very rare. Only a few individuals with each type of the disorder have been identified. | Schindler disease |
What are the genetic changes related to Schindler disease ? | Mutations in the NAGA gene cause Schindler disease. The NAGA gene provides instructions for making the enzyme alpha-N-acetylgalactosaminidase. This enzyme works in the lysosomes, which are compartments within cells that digest and recycle materials. Within lysosomes, the enzyme helps break down complexes called glycoproteins and glycolipids, which consist of sugar molecules attached to certain proteins and fats. Specifically, alpha-N-acetylgalactosaminidase helps remove a molecule called alpha-N-acetylgalactosamine from sugars in these complexes. Mutations in the NAGA gene interfere with the ability of the alpha-N-acetylgalactosaminidase enzyme to perform its role in breaking down glycoproteins and glycolipids. These substances accumulate in the lysosomes and cause cells to malfunction and eventually die. Cell damage in the nervous system and other tissues and organs of the body leads to the signs and symptoms of Schindler disease. | Schindler disease |
Is Schindler disease 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. | Schindler disease |
What are the treatments for Schindler disease ? | These resources address the diagnosis or management of Schindler disease: - Genetic Testing Registry: Kanzaki disease - Genetic Testing Registry: Schindler disease, type 1 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 | Schindler disease |
What is (are) propionic acidemia ? | Propionic acidemia is an inherited disorder in which the body is unable to process certain parts of proteins and lipids (fats) properly. It is classified as an organic acid disorder, which is a condition that leads to an abnormal buildup of particular acids known as organic acids. Abnormal levels of organic acids in the blood (organic acidemia), urine (organic aciduria), and tissues can be toxic and can cause serious health problems. In most cases, the features of propionic acidemia become apparent within a few days after birth. The initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These symptoms sometimes progress to more serious medical problems, including heart abnormalities, seizures, coma, and possibly death. Less commonly, the signs and symptoms of propionic acidemia appear during childhood and may come and go over time. Some affected children experience intellectual disability or delayed development. In children with this later-onset form of the condition, episodes of more serious health problems can be triggered by prolonged periods without food (fasting), fever, or infections. | propionic acidemia |
How many people are affected by propionic acidemia ? | Propionic acidemia affects about 1 in 100,000 people in the United States. The condition appears to be more common in several populations worldwide, including the Inuit population of Greenland, some Amish communities, and Saudi Arabians. | propionic acidemia |
What are the genetic changes related to propionic acidemia ? | Mutations in the PCCA and PCCB genes cause propionic acidemia. The PCCA and PCCB genes provide instructions for making two parts (subunits) of an enzyme called propionyl-CoA carboxylase. This enzyme plays a role in the normal breakdown of proteins. Specifically, it helps process several amino acids, which are the building blocks of proteins. Propionyl-CoA carboxylase also helps break down certain types of fat and cholesterol in the body. Mutations in the PCCA or PCCB gene disrupt the function of the enzyme and prevent the normal breakdown of these molecules. As a result, a substance called propionyl-CoA and other potentially harmful compounds can build up to toxic levels in the body. This buildup damages the brain and nervous system, causing the serious health problems associated with propionic acidemia. | propionic acidemia |
Is propionic acidemia 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. | propionic acidemia |
What are the treatments for propionic acidemia ? | These resources address the diagnosis or management of propionic acidemia: - Baby's First Test - Gene Review: Gene Review: Propionic Acidemia - Genetic Testing Registry: Propionic acidemia 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 | propionic acidemia |
What is (are) 22q13.3 deletion syndrome ? | 22q13.3 deletion syndrome, which is also commonly known as Phelan-McDermid syndrome, is a disorder caused by the loss of a small piece of chromosome 22. The deletion occurs near the end of the chromosome at a location designated q13.3. The features of 22q13.3 deletion syndrome vary widely and involve many parts of the body. Characteristic signs and symptoms include developmental delay, moderate to profound intellectual disability, decreased muscle tone (hypotonia), and absent or delayed speech. Some people with this condition have autism or autistic-like behavior that affects communication and social interaction, such as poor eye contact, sensitivity to touch, and aggressive behaviors. They may also chew on non-food items such as clothing. Less frequently, people with this condition have seizures. Individuals with 22q13.3 deletion syndrome tend to have a decreased sensitivity to pain. Many also have a reduced ability to sweat, which can lead to a greater risk of overheating and dehydration. Some people with this condition have episodes of frequent vomiting and nausea (cyclic vomiting) and backflow of stomach acids into the esophagus (gastroesophageal reflux). People with 22q13.3 deletion syndrome typically have distinctive facial features, including a long, narrow head; prominent ears; a pointed chin; droopy eyelids (ptosis); and deep-set eyes. Other physical features seen with this condition include large and fleshy hands and/or feet, a fusion of the second and third toes (syndactyly), and small or abnormal toenails. Some affected individuals have rapid (accelerated) growth. | 22q13.3 deletion syndrome |
How many people are affected by 22q13.3 deletion syndrome ? | At least 500 cases of 22q13.3 deletion syndrome are known. | 22q13.3 deletion syndrome |
What are the genetic changes related to 22q13.3 deletion syndrome ? | 22q13.3 deletion syndrome is caused by a deletion near the end of the long (q) arm of chromosome 22. The signs and symptoms of 22q13.3 deletion syndrome are probably related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals. A ring chromosome 22 can also cause 22q13.3 deletion syndrome. A ring chromosome is a circular structure that occurs when a chromosome breaks in two places, the tips of the chromosome are lost, and the broken ends fuse together. People with ring chromosome 22 have one copy of this abnormal chromosome in some or all of their cells. Researchers believe that several critical genes near the end of the long (q) arm of chromosome 22 are lost when the ring chromosome 22 forms. If one of the chromosome break points is at position 22q13.3, people with ring chromosome 22 have similar signs and symptoms as those with a simple deletion. Researchers are working to identify all of the genes that contribute to the features of 22q13.3 deletion syndrome. They have determined that the loss of a particular gene on chromosome 22, SHANK3, is likely to be responsible for many of the syndrome's characteristic signs (such as developmental delay, intellectual disability, and impaired speech). Additional genes in the deleted region probably contribute to the varied features of 22q13.3 deletion syndrome. | 22q13.3 deletion syndrome |
Is 22q13.3 deletion syndrome inherited ? | Most cases of 22q13.3 deletion syndrome are not inherited. The deletion occurs most often as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development. Affected people typically have no history of the disorder in their family, though they can pass the chromosome deletion to their children. When 22q13.3 deletion syndrome is inherited, its inheritance pattern is considered autosomal dominant because a deletion in one copy of chromosome 22 in each cell is sufficient to cause the condition. About 15 to 20 percent of people with 22q13.3 deletion syndrome inherit a chromosome abnormality from an unaffected parent. In these cases, the parent carries a chromosomal rearrangement called a balanced translocation, in which a segment from one chromosome has traded places with a segment from another chromosome, but no genetic material is gained or lost. Balanced translocations usually do not cause any health problems; however, they can become unbalanced as they are passed to the next generation. Children who inherit an unbalanced translocation can have a chromosomal rearrangement with extra or missing genetic material. Individuals with 22q13.3 deletion syndrome who inherit an unbalanced translocation are missing genetic material from the long arm of chromosome 22, which results in the health problems characteristic of this disorder. | 22q13.3 deletion syndrome |
What are the treatments for 22q13.3 deletion syndrome ? | These resources address the diagnosis or management of 22q13.3 deletion syndrome: - Gene Review: Gene Review: Phelan-McDermid Syndrome - Genetic Testing Registry: 22q13.3 deletion syndrome - MedlinePlus Encyclopedia: Sweating--absent 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 | 22q13.3 deletion syndrome |
What is (are) Peters plus syndrome ? | Peters plus syndrome is an inherited condition that is characterized by eye abnormalities, short stature, an opening in the lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate), distinctive facial features, and intellectual disability. The eye problems in Peters plus syndrome occur in an area at the front part of the eye known as the anterior segment. The anterior segment consists of structures including the lens, the colored part of the eye (iris), and the clear covering of the eye (cornea). An eye problem called Peters anomaly is the most common anterior segment abnormality seen in Peters plus syndrome. Peters anomaly involves abnormal development of the anterior segment, which results in a cornea that is cloudy (opaque) and causes blurred vision. Peters anomaly may also be associated with clouding of the lenses of the eyes (cataracts) or other lens abnormalities. Peters anomaly is usually bilateral, which means that it affects both eyes. The severity of corneal clouding and other eye problems can vary between individuals with Peters plus syndrome, even among members of the same family. Many people with Peters plus syndrome experience vision loss that worsens over time. All people with Peters plus syndrome have short stature, which is evident before birth. The height of adult males with this condition ranges from 141 centimeters to 155 centimeters (4 feet, 7 inches to 5 feet, 1 inch), and the height of adult females ranges from 128 centimeters to 151 centimeters (4 feet, 2 inches to 4 feet, 11 inches). Individuals with Peters plus syndrome also have shortened upper limbs (rhizomelia) and shortened fingers and toes (brachydactyly). The characteristic facial features of Peters plus syndrome include a prominent forehead; small, malformed ears; narrow eyes; a long area between the nose and mouth (philtrum); and a pronounced double curve of the upper lip (Cupid's bow). The neck may also be broad and webbed. A cleft lip with or without a cleft palate is present in about half of the people with this condition. Developmental milestones, such as walking and speech, are delayed in most children with Peters plus syndrome. Most affected individuals also have intellectual disability that can range from mild to severe, although some have normal intelligence. The severity of physical features does not predict the level of intellectual disability. Less common signs and symptoms of Peters plus syndrome include heart defects, structural brain abnormalities, hearing loss, and kidney or genital abnormalities. | Peters plus syndrome |
How many people are affected by Peters plus syndrome ? | Peters plus syndrome is a rare disorder; its incidence is unknown. Fewer than 80 people with this condition have been reported worldwide. | Peters plus syndrome |
What are the genetic changes related to Peters plus syndrome ? | Mutations in the B3GLCT gene cause Peters plus syndrome. The B3GLCT gene provides instructions for making an enzyme called beta 3-glucosyltransferase (B3Glc-T), which is involved in the complex process of adding sugar molecules to proteins (glycosylation). Glycosylation modifies proteins so they can perform a wider variety of functions. Most mutations in the B3GLCT gene lead to the production of an abnormally short, nonfunctional version of the B3Glc-T enzyme, which disrupts glycosylation. It is unclear how the loss of functional B3Glc-T enzyme leads to the signs and symptoms of Peters plus syndrome, but impaired glycosylation likely disrupts the function of many proteins, which may contribute to the variety of features. | Peters plus syndrome |
Is Peters plus 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. | Peters plus syndrome |
What are the treatments for Peters plus syndrome ? | These resources address the diagnosis or management of Peters plus syndrome: - Gene Review: Gene Review: Peters Plus Syndrome - Genetic Testing Registry: Peters plus 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 | Peters plus syndrome |
What is (are) TK2-related mitochondrial DNA depletion syndrome, myopathic form ? | TK2-related mitochondrial DNA depletion syndrome, myopathic form (TK2-MDS) is an inherited condition that causes progressive muscle weakness (myopathy). The signs and symptoms of TK2-MDS typically begin in early childhood. Development is usually normal early in life, but as muscle weakness progresses, people with TK2-MDS lose motor skills such as standing, walking, eating, and talking. Some affected individuals have increasing weakness in the muscles that control eye movement, leading to droopy eyelids (progressive external ophthalmoplegia). Most often in TK2-MDS, the muscles are the only affected tissues; however, the liver may be enlarged (hepatomegaly), seizures can occur, and hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss) may be present. Intelligence is usually not affected. As the disorder worsens, the muscles that control breathing become weakened and affected individuals frequently have to rely on mechanical ventilation. Respiratory failure is the most common cause of death in people with TK2-MDS, often occurring in childhood. Rarely, the disorder progresses slowly and affected individuals survive into adolescence or adulthood. | TK2-related mitochondrial DNA depletion syndrome, myopathic form |
How many people are affected by TK2-related mitochondrial DNA depletion syndrome, myopathic form ? | The prevalence of TK2-MDS is unknown. Approximately 45 cases have been described. | TK2-related mitochondrial DNA depletion syndrome, myopathic form |
What are the genetic changes related to TK2-related mitochondrial DNA depletion syndrome, myopathic form ? | As the condition name suggests, mutations in the TK2 gene cause TK2-MDS. The TK2 gene provides instructions for making an enzyme called thymidine kinase 2 that functions within cell structures called mitochondria, which are found in all tissues. Mitochondria are involved in a wide variety of cellular activities, including energy production; chemical signaling; and regulation of cell growth, cell division, and cell death. Mitochondria contain their own genetic material, known as mitochondrial DNA (mtDNA), which is essential for the normal function of these structures. Thymidine kinase 2 is involved in the production and maintenance of mtDNA. Specifically, this enzyme plays a role in recycling mtDNA building blocks (nucleotides) so that errors in mtDNA sequencing can be repaired and new mtDNA molecules can be produced. Mutations in the TK2 gene reduce the production or activity of thymidine kinase 2. A decrease in enzyme activity impairs recycling of mtDNA nucleotides, causing a shortage of nucleotides available for the repair and production of mtDNA molecules. A reduction in the amount of mtDNA (known as mtDNA depletion) impairs mitochondrial function. Greater mtDNA depletion tends to cause more severe signs and symptoms. The muscle cells of people with TK2-MDS have very low amounts of mtDNA, ranging from 5 to 30 percent of normal. Other tissues can have 60 percent of normal to normal amounts of mtDNA. It is unclear why TK2 gene mutations typically affect only muscle tissue, but the high energy demands of muscle cells may make them the most susceptible to cell death when mtDNA is lost and less energy is produced in cells. The brain and the liver also have high energy demands, which may explain why these organs are affected in severe cases of TK2-MDS. | TK2-related mitochondrial DNA depletion syndrome, myopathic form |
Is TK2-related mitochondrial DNA depletion syndrome, myopathic form 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. | TK2-related mitochondrial DNA depletion syndrome, myopathic form |
What are the treatments for TK2-related mitochondrial DNA depletion syndrome, myopathic form ? | These resources address the diagnosis or management of TK2-related mitochondrial DNA depletion syndrome, myopathic form: - Cincinnati Children's Hospital: Mitochondrial Diseases Program - Gene Review: Gene Review: TK2-Related Mitochondrial DNA Depletion Syndrome, Myopathic Form 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 | TK2-related mitochondrial DNA depletion syndrome, myopathic form |
What is (are) Pol III-related leukodystrophy ? | Pol III-related leukodystrophy is a disorder that affects the nervous system and other parts of the body. Leukodystrophies are conditions that involve abnormalities of the nervous system's white matter, which consists of nerve fibers covered by a fatty substance called myelin. Myelin insulates nerve fibers and promotes the rapid transmission of nerve impulses. Pol III-related leukodystrophy is a hypomyelinating disease, which means that the nervous system of affected individuals has a reduced ability to form myelin. Hypomyelination underlies most of the neurological problems associated with Pol III-related leukodystrophy. A small number of people with this disorder also have a loss of nerve cells in a part of the brain involved in coordinating movements (cerebellar atrophy) and underdevelopment (hypoplasia) of tissue that connects the left and right halves of the brain (the corpus callosum). These brain abnormalities likely contribute to the neurological problems in affected individuals. People with Pol III-related leukodystrophy usually have intellectual disability ranging from mild to severe, which gradually worsens over time. Some affected individuals have normal intelligence in early childhood but develop mild intellectual disability during the course of the disease. Difficulty coordinating movements (ataxia), which begins in childhood and slowly worsens over time, is a characteristic feature of Pol III-related leukodystrophy. Affected children typically have delayed development of motor skills such as walking. Their gait is unstable, and they usually walk with their feet wide apart for balance. Affected individuals may eventually need to use a walker or wheelchair. Involuntary rhythmic shaking (tremor) of the arms and hands may occur in this disorder. In some cases the tremor occurs mainly during movement (intentional tremor); other affected individuals experience the tremor both during movement and at rest. Development of the teeth (dentition) is often abnormal in Pol III-related leukodystrophy, resulting in the absence of some teeth (known as hypodontia or oligodontia). Some affected infants are born with a few teeth (natal teeth), which fall out during the first weeks of life. The primary (deciduous) teeth appear later than usual, beginning at about age 2. In Pol III-related leukodystrophy, the teeth may not appear in the usual sequence, in which front teeth (incisors) appear before back teeth (molars). Instead, molars often appear first, with incisors appearing later or not at all. Permanent teeth are also delayed, and may not appear until adolescence. The teeth may also be unusually shaped. Some individuals with Pol III-related leukodystrophy have excessive salivation and difficulty chewing or swallowing (dysphagia), which can lead to choking. They may also have speech impairment (dysarthria). People with Pol III-related leukodystrophy often have abnormalities in eye movement, such as progressive vertical gaze palsy, which is restricted up-and-down eye movement that worsens over time. Nearsightedness is common in affected individuals, and clouding of the lens of the eyes (cataracts) has also been reported. Deterioration (atrophy) of the nerves that carry information from the eyes to the brain (the optic nerves) and seizures may also occur in this disorder. Hypogonadotropic hypogonadism, which is a condition caused by reduced production of hormones that direct sexual development, may occur in Pol III-related leukodystrophy. Affected individuals have delayed development of the typical signs of puberty, such as the growth of body hair. People with Pol III-related leukodystrophy may have different combinations of its signs and symptoms. These varied combinations of clinical features were originally described as separate disorders. Affected individuals may be diagnosed with ataxia, delayed dentition, and hypomyelination (ADDH); hypomyelination, hypodontia, hypogonadotropic hypogonadism (4H syndrome); tremor-ataxia with central hypomyelination (TACH); leukodystrophy with oligodontia (LO); or hypomyelination with cerebellar atrophy and hypoplasia of the corpus callosum (HCAHC). Because these disorders were later found to have the same genetic cause, researchers now group them as variations of the single condition Pol III-related leukodystrophy. | Pol III-related leukodystrophy |
How many people are affected by Pol III-related leukodystrophy ? | Pol III-related leukodystrophy is a rare disorder; its prevalence is unknown. Only about 40 cases have been described in the medical literature. However, researchers believe that a significant percentage of people with an unspecified hypomyelinating leukodystrophy could have Pol III-related leukodystrophy. | Pol III-related leukodystrophy |
What are the genetic changes related to Pol III-related leukodystrophy ? | Pol III-related leukodystrophy is caused by mutations in the POLR3A or POLR3B gene. These genes provide instructions for making the two largest parts (subunits) of an enzyme called RNA polymerase III. This enzyme is involved in the production (synthesis) of ribonucleic acid (RNA), a chemical cousin of DNA. The RNA polymerase III enzyme attaches (binds) to DNA and synthesizes RNA in accordance with the instructions carried by the DNA, a process called transcription. RNA polymerase III helps synthesize several forms of RNA, including ribosomal RNA (rRNA) and transfer RNA (tRNA). Molecules of rRNA and tRNA assemble protein building blocks (amino acids) into working proteins; this process is essential for the normal functioning and survival of cells. Researchers suggest that mutations in the POLR3A or POLR3B gene may impair the ability of subunits of the RNA polymerase III enzyme to assemble properly or result in an RNA polymerase III with impaired ability to bind to DNA. Reduced function of the RNA polymerase III molecule likely affects development and function of many parts of the body, including the nervous system and the teeth, but the relationship between POLR3A and POLR3B gene mutations and the specific signs and symptoms of Pol III-related leukodystrophy is unknown. | Pol III-related leukodystrophy |
Is Pol III-related leukodystrophy 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. | Pol III-related leukodystrophy |
What are the treatments for Pol III-related leukodystrophy ? | These resources address the diagnosis or management of Pol III-related leukodystrophy: - Eastman Dental Hospital: Hypodontia Clinic - Gene Review: Gene Review: Pol III-Related Leukodystrophies - Genetic Testing Registry: Pol III-related leukodystrophy - Johns Hopkins Medicine: Treating Ataxia - National Ataxia Foundation: Diagnosis of Ataxia - UCSF Benioff Children's Hospital: Hypodontia - University of Chicago Ataxia Center 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 | Pol III-related leukodystrophy |
What is (are) VACTERL association ? | VACTERL association is a disorder that affects many body systems. VACTERL stands for vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities. People diagnosed with VACTERL association typically have at least three of these characteristic features. Affected individuals may have additional abnormalities that are not among the characteristic features of VACTERL association. Defects in the bones of the spine (vertebrae) are present in 60 to 80 percent of people with VACTERL association. These defects may include misshapen vertebrae, fused vertebrae, and missing or extra vertebrae. In some people, spinal problems require surgery or cause health problems, such as back pain of varying severity, throughout life. Sixty to 90 percent of individuals with VACTERL association have narrowing or blockage of the anus (anal atresia). Anal atresia may be accompanied by abnormalities of the genitalia and urinary tract (genitourinary anomalies). Heart (cardiac) defects occur in 40 to 80 percent of individuals with VACTERL association. Cardiac defects can range in severity from a life-threatening problem to a subtle defect that does not cause health problems. Fifty to 80 percent of people with VACTERL association have a tracheo-esophageal fistula, which is an abnormal connection (fistula) between the esophagus and the windpipe (trachea). Tracheo-esophageal fistula can cause problems with breathing and feeding early in life and typically requires surgical correction in infancy. Kidney (renal) anomalies occur in 50 to 80 percent of individuals with VACTERL association. Affected individuals may be missing one or both kidneys or have abnormally developed or misshapen kidneys, which can affect kidney function. Limb abnormalities are seen in 40 to 50 percent of people with VACTERL association. These abnormalities most commonly include poorly developed or missing thumbs or underdeveloped forearms and hands. Some of the features of VACTERL association can be subtle and are not identified until late in childhood or adulthood, making diagnosis of this condition difficult. | VACTERL association |
How many people are affected by VACTERL association ? | VACTERL association occurs in 1 in 10,000 to 40,000 newborns. | VACTERL association |
What are the genetic changes related to VACTERL association ? | VACTERL association is a complex condition that may have different causes in different people. In some people, the condition is likely caused by the interaction of multiple genetic and environmental factors. Some possible genetic and environmental influences have been identified and are being studied. The developmental abnormalities characteristic of VACTERL association develop before birth. The disruption to fetal development that causes VACTERL association likely occurs early in development, resulting in birth defects that affect multiple body systems. It is unclear why the features characteristic of VACTERL association group together in affected individuals. | VACTERL association |
Is VACTERL association inherited ? | Most cases of VACTERL association are sporadic, which means they occur in people with no history of the condition in their family. Rarely, families have multiple people affected with VACTERL association. A few affected individuals have family members with one or two features, but not enough signs to be diagnosed with the condition. In these families, the features of VACTERL association often do not have a clear pattern of inheritance. Multiple genetic and environmental factors likely play a part in determining the risk of developing this condition and how severe the condition will be in an individual. | VACTERL association |
What are the treatments for VACTERL association ? | These resources address the diagnosis or management of VACTERL association: - MedlinePlus Encyclopedia: Tracheoesophageal Fistula and Esophageal Atresia Repair 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 | VACTERL association |
What is (are) dihydropyrimidinase deficiency ? | Dihydropyrimidinase deficiency is a disorder that can cause neurological and gastrointestinal problems in some affected individuals. Other people with dihydropyrimidinase deficiency have no signs or symptoms related to the disorder, and in these individuals the condition can be diagnosed only by laboratory testing. The neurological abnormalities that occur most often in people with dihydropyrimidinase deficiency are intellectual disability, seizures, and weak muscle tone (hypotonia). An abnormally small head size (microcephaly) and autistic behaviors that affect communication and social interaction also occur in some individuals with this condition. Gastrointestinal problems that occur in dihydropyrimidinase deficiency include backflow of acidic stomach contents into the esophagus (gastroesophageal reflux) and recurrent episodes of vomiting (cyclic vomiting). Affected individuals can also have deterioration (atrophy) of the small, finger-like projections (villi) that line the small intestine and provide a large surface area with which to absorb nutrients. This condition, called villous atrophy, can lead to difficulty absorbing nutrients from foods (malabsorption), resulting in a failure to grow and gain weight at the expected rate (failure to thrive). People with dihydropyrimidinase deficiency, including those who otherwise exhibit no symptoms, may be vulnerable to severe, potentially life-threatening toxic reactions to certain drugs called fluoropyrimidines that are used to treat cancer. Common examples of these drugs are 5-fluorouracil and capecitabine. These drugs may not be broken down efficiently and can build up to toxic levels in the body (fluoropyrimidine toxicity), leading to drug reactions including gastrointestinal problems, blood abnormalities, and other signs and symptoms. | dihydropyrimidinase deficiency |
How many people are affected by dihydropyrimidinase deficiency ? | Dihydropyrimidinase deficiency is thought to be a rare disorder. Only a few dozen affected individuals have been described in the medical literature. | dihydropyrimidinase deficiency |
What are the genetic changes related to dihydropyrimidinase deficiency ? | Dihydropyrimidinase deficiency is caused by mutations in the DPYS gene, which provides instructions for making an enzyme called dihydropyrimidinase. This enzyme is involved in the breakdown of molecules called pyrimidines, which are building blocks of DNA and its chemical cousin RNA. The dihydropyrimidinase enzyme is involved in the second step of the three-step process that breaks down pyrimidines. This step opens the ring-like structures of molecules called 5,6-dihydrothymine and 5,6-dihydrouracil so that these molecules can be further broken down. The DPYS gene mutations that cause dihydropyrimidinase deficiency greatly reduce or eliminate dihydropyrimidinase enzyme function. As a result, the enzyme is unable to begin the breakdown of 5,6-dihydrothymine and 5,6-dihydrouracil. Excessive amounts of these molecules accumulate in the blood and in the fluid that surrounds and protects the brain and spinal cord (the cerebrospinal fluid or CSF) and are released in the urine. The relationship between the inability to break down 5,6-dihydrothymine and 5,6-dihydrouracil and the specific features of dihydropyrimidinase deficiency is unclear. Failure to complete this step in the breakdown of pyrimidines also impedes the final step of the process, which produces molecules called beta-aminoisobutyric acid and beta-alanine. Both of these molecules are thought to protect the nervous system and help it function properly. Reduced production of beta-aminoisobutyric acid and beta-alanine may impair the function of these molecules in the nervous system, leading to neurological problems in some people with dihydropyrimidinase deficiency. Because fluoropyrimidine drugs are broken down by the same three-step process as pyrimidines, deficiency of the dihydropyrimidinase enzyme could lead to the drug buildup that causes fluoropyrimidine toxicity. It is unknown why some people with dihydropyrimidinase deficiency do not develop health problems related to the condition; other genetic and environmental factors likely help determine the effects of this disorder. | dihydropyrimidinase deficiency |
Is dihydropyrimidinase 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. | dihydropyrimidinase deficiency |
What are the treatments for dihydropyrimidinase deficiency ? | These resources address the diagnosis or management of dihydropyrimidinase deficiency: - Genetic Testing Registry: Dihydropyrimidinase deficiency 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 | dihydropyrimidinase deficiency |
What is (are) neurofibromatosis type 1 ? | Neurofibromatosis type 1 is a condition characterized by changes in skin coloring (pigmentation) and the growth of tumors along nerves in the skin, brain, and other parts of the body. The signs and symptoms of this condition vary widely among affected people. Beginning in early childhood, almost all people with neurofibromatosis type 1 have multiple caf-au-lait spots, which are flat patches on the skin that are darker than the surrounding area. These spots increase in size and number as the individual grows older. Freckles in the underarms and groin typically develop later in childhood. Most adults with neurofibromatosis type 1 develop neurofibromas, which are noncancerous (benign) tumors that are usually located on or just under the skin. These tumors may also occur in nerves near the spinal cord or along nerves elsewhere in the body. Some people with neurofibromatosis type 1 develop cancerous tumors that grow along nerves. These tumors, which usually develop in adolescence or adulthood, are called malignant peripheral nerve sheath tumors. People with neurofibromatosis type 1 also have an increased risk of developing other cancers, including brain tumors and cancer of blood-forming tissue (leukemia). During childhood, benign growths called Lisch nodules often appear in the colored part of the eye (the iris). Lisch nodules do not interfere with vision. Some affected individuals also develop tumors that grow along the nerve leading from the eye to the brain (the optic nerve). These tumors, which are called optic gliomas, may lead to reduced vision or total vision loss. In some cases, optic gliomas have no effect on vision. Additional signs and symptoms of neurofibromatosis type 1 include high blood pressure (hypertension), short stature, an unusually large head (macrocephaly), and skeletal abnormalities such as an abnormal curvature of the spine (scoliosis). Although most people with neurofibromatosis type 1 have normal intelligence, learning disabilities and attention deficit hyperactivity disorder (ADHD) occur frequently in affected individuals. | neurofibromatosis type 1 |
How many people are affected by neurofibromatosis type 1 ? | Neurofibromatosis type 1 occurs in 1 in 3,000 to 4,000 people worldwide. | neurofibromatosis type 1 |
What are the genetic changes related to neurofibromatosis type 1 ? | Mutations in the NF1 gene cause neurofibromatosis type 1. The NF1 gene provides instructions for making a protein called neurofibromin. This protein is produced in many cells, including nerve cells and specialized cells surrounding nerves (oligodendrocytes and Schwann cells). Neurofibromin acts as a tumor suppressor, which means that it keeps cells from growing and dividing too rapidly or in an uncontrolled way. Mutations in the NF1 gene lead to the production of a nonfunctional version of neurofibromin that cannot regulate cell growth and division. As a result, tumors such as neurofibromas can form along nerves throughout the body. It is unclear how mutations in the NF1 gene lead to the other features of neurofibromatosis type 1, such as caf-au-lait spots and learning disabilities. | neurofibromatosis type 1 |
Is neurofibromatosis type 1 inherited ? | Neurofibromatosis type 1 is considered to have an autosomal dominant pattern of inheritance. People with this condition are born with one mutated copy of the NF1 gene in each cell. In about half of cases, the altered gene is inherited from an affected parent. The remaining cases result from new mutations in the NF1 gene and occur in people with no history of the disorder in their family. Unlike most other autosomal dominant conditions, in which one altered copy of a gene in each cell is sufficient to cause the disorder, two copies of the NF1 gene must be altered to trigger tumor formation in neurofibromatosis type 1. A mutation in the second copy of the NF1 gene occurs during a person's lifetime in specialized cells surrounding nerves. Almost everyone who is born with one NF1 mutation acquires a second mutation in many cells and develops the tumors characteristic of neurofibromatosis type 1. | neurofibromatosis type 1 |
What are the treatments for neurofibromatosis type 1 ? | These resources address the diagnosis or management of neurofibromatosis type 1: - Gene Review: Gene Review: Neurofibromatosis 1 - Genetic Testing Registry: Neurofibromatosis, type 1 - MedlinePlus Encyclopedia: Neurofibromatosis-1 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 | neurofibromatosis type 1 |
What is (are) alpha thalassemia ? | Alpha thalassemia is a blood disorder that reduces the production of hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body. In people with the characteristic features of alpha thalassemia, a reduction in the amount of hemoglobin prevents enough oxygen from reaching the body's tissues. Affected individuals also have a shortage of red blood cells (anemia), which can cause pale skin, weakness, fatigue, and more serious complications. Two types of alpha thalassemia can cause health problems. The more severe type is known as hemoglobin Bart hydrops fetalis syndrome or Hb Bart syndrome. The milder form is called HbH disease. Hb Bart syndrome is characterized by hydrops fetalis, a condition in which excess fluid builds up in the body before birth. Additional signs and symptoms can include severe anemia, an enlarged liver and spleen (hepatosplenomegaly), heart defects, and abnormalities of the urinary system or genitalia. As a result of these serious health problems, most babies with this condition are stillborn or die soon after birth. Hb Bart syndrome can also cause serious complications for women during pregnancy, including dangerously high blood pressure with swelling (preeclampsia), premature delivery, and abnormal bleeding. HbH disease causes mild to moderate anemia, hepatosplenomegaly, and yellowing of the eyes and skin (jaundice). Some affected individuals also have bone changes such as overgrowth of the upper jaw and an unusually prominent forehead. The features of HbH disease usually appear in early childhood, and affected individuals typically live into adulthood. | alpha thalassemia |
How many people are affected by alpha thalassemia ? | Alpha thalassemia is a fairly common blood disorder worldwide. Thousands of infants with Hb Bart syndrome and HbH disease are born each year, particularly in Southeast Asia. Alpha thalassemia also occurs frequently in people from Mediterranean countries, North Africa, the Middle East, India, and Central Asia. | alpha thalassemia |
What are the genetic changes related to alpha thalassemia ? | Alpha thalassemia typically results from deletions involving the HBA1 and HBA2 genes. Both of these genes provide instructions for making a protein called alpha-globin, which is a component (subunit) of hemoglobin. People have two copies of the HBA1 gene and two copies of the HBA2 gene in each cell. Each copy is called an allele. For each gene, one allele is inherited from a person's father, and the other is inherited from a person's mother. As a result, there are four alleles that produce alpha-globin. The different types of alpha thalassemia result from the loss of some or all of these alleles. Hb Bart syndrome, the most severe form of alpha thalassemia, results from the loss of all four alpha-globin alleles. HbH disease is caused by a loss of three of the four alpha-globin alleles. In these two conditions, a shortage of alpha-globin prevents cells from making normal hemoglobin. Instead, cells produce abnormal forms of hemoglobin called hemoglobin Bart (Hb Bart) or hemoglobin H (HbH). These abnormal hemoglobin molecules cannot effectively carry oxygen to the body's tissues. The substitution of Hb Bart or HbH for normal hemoglobin causes anemia and the other serious health problems associated with alpha thalassemia. Two additional variants of alpha thalassemia are related to a reduced amount of alpha-globin. Because cells still produce some normal hemoglobin, these variants tend to cause few or no health problems. A loss of two of the four alpha-globin alleles results in alpha thalassemia trait. People with alpha thalassemia trait may have unusually small, pale red blood cells and mild anemia. A loss of one alpha-globin allele is found in alpha thalassemia silent carriers. These individuals typically have no thalassemia-related signs or symptoms. | alpha thalassemia |
Is alpha thalassemia inherited ? | The inheritance of alpha thalassemia is complex. Each person inherits two alpha-globin alleles from each parent. If both parents are missing at least one alpha-globin allele, their children are at risk of having Hb Bart syndrome, HbH disease, or alpha thalassemia trait. The precise risk depends on how many alleles are missing and which combination of the HBA1 and HBA2 genes is affected. | alpha thalassemia |
What are the treatments for alpha thalassemia ? | These resources address the diagnosis or management of alpha thalassemia: - Gene Review: Gene Review: Alpha-Thalassemia - Genetic Testing Registry: alpha Thalassemia - MedlinePlus Encyclopedia: Thalassemia - University of California, San Francisco Fetal Treatment Center: Stem Cell Treatments 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 | alpha thalassemia |
What is (are) Langerhans cell histiocytosis ? | Langerhans cell histiocytosis is a disorder in which excess immune system cells called Langerhans cells build up in the body. Langerhans cells, which help regulate the immune system, are normally found throughout the body, especially in the skin, lymph nodes, spleen, lungs, liver, and bone marrow. In Langerhans cell histiocytosis, excess immature Langerhans cells usually form tumors called granulomas. However, Langerhans cell histiocytosis is not generally considered to be a form of cancer. In approximately 80 percent of affected individuals, one or more granulomas develop in the bones, causing pain and swelling. The granulomas, which usually occur in the skull or the long bones of the arms or legs, may cause the bone to fracture. Granulomas also frequently occur in the skin, appearing as blisters, reddish bumps, or rashes which can be mild to severe. The pituitary gland may also be affected; this gland is located at the base of the brain and produces hormones that control many important body functions. Without hormone supplementation, affected individuals may experience delayed or absent puberty or an inability to have children (infertility). In addition, pituitary gland damage may result in the production of excessive amounts of urine (diabetes insipidus) and dysfunction of another gland called the thyroid. Thyroid dysfunction can affect the rate of chemical reactions in the body (metabolism), body temperature, skin and hair texture, and behavior. In 15 to 20 percent of cases, Langerhans cell histiocytosis affects the lungs, liver, or blood-forming (hematopoietic) system; damage to these organs and tissues may be life-threatening. Lung involvement, which appears as swelling of the small airways (bronchioles) and blood vessels of the lungs, results in stiffening of the lung tissue, breathing problems, and increased risk of infection. Hematopoietic involvement, which occurs when the Langerhans cells crowd out blood-forming cells in the bone marrow, leads to a general reduction in the number of blood cells (pancytopenia). Pancytopenia results in fatigue due to low numbers of red blood cells (anemia), frequent infections due to low numbers of white blood cells (neutropenia), and clotting problems due to low numbers of platelets (thrombocytopenia). Other signs and symptoms that may occur in Langerhans cell histiocytosis, depending on which organs and tissues have Langerhans cell deposits, include swollen lymph nodes, abdominal pain, yellowing of the skin and whites of the eyes (jaundice), delayed puberty, protruding eyes, dizziness, irritability, and seizures. About 1 in 50 affected individuals experience deterioration of neurological function (neurodegeneration). Langerhans cell histiocytosis is often diagnosed in childhood, usually between ages 2 and 3, but can appear at any age. Most individuals with adult-onset Langerhans cell histiocytosis are current or past smokers; in about two-thirds of adult-onset cases the disorder affects only the lungs. The severity of Langerhans cell histiocytosis, and its signs and symptoms, vary widely among affected individuals. Certain presentations or forms of the disorder were formerly considered to be separate diseases. Older names that were sometimes used for forms of Langerhans cell histiocytosis include eosinophilic granuloma, Hand-Schller-Christian disease, and Letterer-Siwe disease. In many people with Langerhans cell histiocytosis, the disorder eventually goes away with appropriate treatment. It may even disappear on its own, especially if the disease occurs only in the skin. However, some complications of the condition, such as diabetes insipidus or other effects of tissue and organ damage, may be permanent. | Langerhans cell histiocytosis |
How many people are affected by Langerhans cell histiocytosis ? | Langerhans cell histiocytosis is a rare disorder. Its prevalence is estimated at 1 to 2 in 100,000 people. | Langerhans cell histiocytosis |
What are the genetic changes related to Langerhans cell histiocytosis ? | Somatic mutations in the BRAF gene have been identified in the Langerhans cells of about half of individuals with Langerhans cell histiocytosis. Somatic gene mutations are acquired during a person's lifetime and are present only in certain cells. These changes are not inherited. The BRAF gene provides instructions for making a protein that is normally switched on and off in response to signals that control cell growth and development. Somatic mutations cause the BRAF protein in affected cells to be continuously active and to transmit messages to the nucleus even in the absence of these chemical signals. The overactive protein may contribute to the development of Langerhans cell histiocytosis by allowing the Langerhans cells to grow and divide uncontrollably. Changes in other genes have also been identified in the Langerhans cells of some individuals with Langerhans cell histiocytosis. Some researchers believe that additional factors, such as viral infections and environmental toxins, may also influence the development of this complex disorder. | Langerhans cell histiocytosis |
Is Langerhans cell histiocytosis inherited ? | Langerhans cell histiocytosis is usually not inherited and typically occurs in people with no history of the disorder in their family. A few families with multiple cases of Langerhans cell histiocytosis have been identified, but the inheritance pattern is unknown. | Langerhans cell histiocytosis |
What are the treatments for Langerhans cell histiocytosis ? | These resources address the diagnosis or management of Langerhans cell histiocytosis: - Cincinnati Children's Hospital Medical Center - Cleveland Clinic - Genetic Testing Registry: Langerhans cell histiocytosis, multifocal - National Cancer Institute: Langerhans Cell Histiocytosis Treatment - Seattle Children's Hospital - St. Jude Children's Research Hospital - Sydney Children's Hospital 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 | Langerhans cell histiocytosis |
What is (are) granulomatosis with polyangiitis ? | Granulomatosis with polyangiitis (GPA) is a condition that causes inflammation that primarily affects the respiratory tract (including the lungs and airways) and the kidneys. This disorder is also commonly known as Wegener granulomatosis. A characteristic feature of GPA is inflammation of blood vessels (vasculitis), particularly the small- and medium-sized blood vessels in the lungs, nose, sinuses, windpipe, and kidneys, although vessels in any organ can be involved. Polyangiitis refers to the inflammation of multiple types of vessels, such as small arteries and veins. Vasculitis causes scarring and tissue death in the vessels and impedes blood flow to tissues and organs. Another characteristic feature of GPA is the formation of granulomas, which are small areas of inflammation composed of immune cells that aid in the inflammatory reaction. The granulomas usually occur in the lungs or airways of people with this condition, although they can occur in the eyes or other organs. As granulomas grow, they can invade surrounding areas, causing tissue damage. The signs and symptoms of GPA vary based on the tissues and organs affected by vasculitis. Many people with this condition experience a vague feeling of discomfort (malaise), fever, weight loss, or other general symptoms of the body's immune reaction. In most people with GPA, inflammation begins in the vessels of the respiratory tract, leading to nasal congestion, frequent nosebleeds, shortness of breath, or coughing. Severe inflammation in the nose can lead to a hole in the tissue that separates the two nostrils (nasal septum perforation) or a collapse of the septum, causing a sunken bridge of the nose (saddle nose). The kidneys are commonly affected in people with GPA. Tissue damage caused by vasculitis in the kidneys can lead to decreased kidney function, which may cause increased blood pressure or blood in the urine, and life-threatening kidney failure. Inflammation can also occur in other regions of the body, including the eyes, middle and inner ear structures, skin, joints, nerves, heart, and brain. Depending on which systems are involved, additional symptoms can include skin rashes, inner ear pain, swollen and painful joints, and numbness or tingling in the limbs. GPA is most common in middle-aged adults, although it can occur at any age. If untreated, the condition is usually fatal within 2 years of diagnosis. Even after treatment, vasculitis can return. | granulomatosis with polyangiitis |
How many people are affected by granulomatosis with polyangiitis ? | GPA is a rare disorder that affects an estimated 3 in 100,000 people in the United States. | granulomatosis with polyangiitis |
What are the genetic changes related to granulomatosis with polyangiitis ? | The genetic basis of GPA is not well understood. Having a particular version of the HLA-DPB1 gene is the strongest genetic risk factor for developing this condition, although several other genes, some of which have not been identified, may be involved. It is likely that a combination of genetic and environmental factors lead to GPA. GPA is an autoimmune disorder. Such disorders occur when the immune system malfunctions and attacks the body's own tissues and organs. Approximately 90 percent of people with GPA have an abnormal immune protein called an anti-neutrophil cytoplasmic antibody (ANCA) in their blood. Antibodies normally bind to specific foreign particles and germs, marking them for destruction, but ANCAs attack normal human proteins. Most people with GPA have an ANCA that attacks the human protein proteinase 3 (PR3). A few affected individuals have an ANCA that attacks a protein called myeloperoxidase (MPO). When these antibodies attach to the protein they recognize, they trigger inflammation, which contributes to the signs and symptoms of GPA. The HLA-DPB1 gene belongs 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. A particular variant of the HLA-DPB1 gene called HLA-DPB1*0401 has been found more frequently in people with GPA, especially those with ANCAs, than in people without the condition. Because the HLA-DPB1 gene is involved in the immune system, changes in it might be related to the autoimmune response and inflammation in the respiratory tract and kidneys characteristic of GPA. However, it is unclear what specific role the HLA-DPB1*0401 gene variant plays in development of this condition. | granulomatosis with polyangiitis |
Is granulomatosis with polyangiitis inherited ? | The inheritance pattern of GPA is unknown. Most instances are sporadic and occur in individuals with no history of the disorder in their family. Only rarely is more than one member of the same family affected by the disorder. | granulomatosis with polyangiitis |
What are the treatments for granulomatosis with polyangiitis ? | These resources address the diagnosis or management of granulomatosis with polyangiitis: - Genetic Testing Registry: Wegener's granulomatosis - Johns Hopkins Vasculitis Center: How is Wegener's Granulomatosis Diagnosed? - MedlinePlus Encyclopedia: Wegener's Granulomatosis - Merck Manual Home Health Edition 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 | granulomatosis with polyangiitis |
What is (are) achondrogenesis ? | Achondrogenesis is a group of severe disorders that affect cartilage and bone development. These conditions are characterized by a small body, short limbs, and other skeletal abnormalities. As a result of serious health problems, infants with achondrogenesis usually die before birth, are stillborn, or die soon after birth from respiratory failure. However, some infants have lived for a short time with intensive medical support. Researchers have described at least three forms of achondrogenesis, designated as type 1A, type 1B, and type 2. The types are distinguished by their signs and symptoms, inheritance pattern, and genetic cause. However, types 1A and 1B are often hard to tell apart without genetic testing. Achondrogenesis type 1A, which is also called the Houston-Harris type, is the least well understood of the three forms. Affected infants have extremely short limbs, a narrow chest, short ribs that fracture easily, and a lack of normal bone formation (ossification) in the skull, spine, and pelvis. Achondrogenesis type 1B, also known as the Parenti-Fraccaro type, is characterized by extremely short limbs, a narrow chest, and a prominent, rounded abdomen. The fingers and toes are short and the feet may turn inward and upward (clubfeet). Affected infants frequently have a soft out-pouching around the belly-button (an umbilical hernia) or near the groin (an inguinal hernia). Infants with achondrogenesis type 2, which is sometimes called the Langer-Saldino type, have short arms and legs, a narrow chest with short ribs, and underdeveloped lungs. This condition is also associated with a lack of ossification in the spine and pelvis. Distinctive facial features include a prominent forehead, a small chin, and, in some cases, an opening in the roof of the mouth (a cleft palate). The abdomen is enlarged, and affected infants often have a condition called hydrops fetalis, in which excess fluid builds up in the body before birth. | achondrogenesis |
How many people are affected by achondrogenesis ? | Achondrogenesis types 1A and 1B are rare genetic disorders; their incidence is unknown. Combined, achondrogenesis type 2 and hypochondrogenesis (a similar skeletal disorder) occur in 1 in 40,000 to 60,000 newborns. | achondrogenesis |
What are the genetic changes related to achondrogenesis ? | Mutations in the TRIP11, SLC26A2, and COL2A1 genes cause achondrogenesis type 1A, type 1B, and type 2, respectively. The genetic cause of achondrogenesis type 1A was unknown until recently, when researchers discovered that the condition can result from mutations in the TRIP11 gene. This gene provides instructions for making a protein called GMAP-210. This protein plays a critical role in the Golgi apparatus, a cell structure in which newly produced proteins are modified so they can carry out their functions. Mutations in the TRIP11 gene prevent the production of functional GMAP-210, which alters the structure and function of the Golgi apparatus. Researchers suspect that cells called chondrocytes in the developing skeleton may be most sensitive to these changes. Chondrocytes give rise to 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. Malfunction of the Golgi apparatus in chondrocytes likely underlies the problems with bone formation in achondrogenesis type 1A. Achondrogenesis type 1B is the most severe of a spectrum of skeletal disorders caused by mutations in the SLC26A2 gene. This gene provides instructions for making a protein that is essential for the normal development of cartilage and for its conversion to bone. Mutations in the SLC26A2 gene cause the skeletal problems characteristic of achondrogenesis type 1B by disrupting the structure of developing cartilage, which prevents bones from forming properly. Achondrogenesis type 2 is one of several skeletal disorders that result from mutations in the COL2A1 gene. This gene provides instructions for making a protein that forms type II collagen. This type of collagen is found mostly in cartilage and in the clear gel that fills the eyeball (the vitreous). It is essential for the normal development of bones and other connective tissues that form the body's supportive framework. Mutations in the COL2A1 gene interfere with the assembly of type II collagen molecules, which prevents bones and other connective tissues from developing properly. | achondrogenesis |
Is achondrogenesis inherited ? | Achondrogenesis type 1A and type 1B both have an autosomal recessive pattern of inheritance, which means both copies of the TRIP11 or SLC26A2 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. Achondrogenesis type 2 is considered an autosomal dominant disorder because one copy of the altered gene in each cell is sufficient to cause the condition. It is almost always caused by new mutations in the COL2A1 gene and typically occurs in people with no history of the disorder in their family. | achondrogenesis |
What are the treatments for achondrogenesis ? | These resources address the diagnosis or management of achondrogenesis: - Gene Review: Gene Review: Achondrogenesis Type 1B - Genetic Testing Registry: Achondrogenesis type 2 - Genetic Testing Registry: Achondrogenesis, type IA - Genetic Testing Registry: Achondrogenesis, type IB - MedlinePlus Encyclopedia: Achondrogenesis 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 | achondrogenesis |
What is (are) Andermann syndrome ? | Andermann syndrome is a disorder that damages the nerves used for muscle movement and sensation (motor and sensory neuropathy). Absence (agenesis) or malformation of the tissue connecting the left and right halves of the brain (corpus callosum) also occurs in most people with this disorder. People affected by Andermann syndrome have abnormal or absent reflexes (areflexia) and weak muscle tone (hypotonia). They experience muscle wasting (amyotrophy), severe progressive weakness and loss of sensation in the limbs, and rhythmic shaking (tremors). They typically begin walking between ages 3 and 4 and lose this ability by their teenage years. As they get older, people with this disorder frequently develop joint deformities called contractures, which restrict the movement of certain joints. Most affected individuals also develop abnormal curvature of the spine (scoliosis), which may require surgery. Andermann syndrome also results in abnormal function of certain cranial nerves, which emerge directly from the brain and extend to various areas of the head and neck. Cranial nerve problems may result in facial muscle weakness, drooping eyelids (ptosis), and difficulty following movements with the eyes (gaze palsy). Individuals with Andermann syndrome usually have intellectual disability, which may be mild to severe, and some experience seizures. They may also develop psychiatric symptoms such as depression, anxiety, agitation, paranoia, and hallucinations, which usually appear in adolescence. Some people with Andermann syndrome have atypical physical features such as widely spaced eyes (ocular hypertelorism); a wide, short skull (brachycephaly); a high arch of the hard palate at the roof of the mouth; a big toe that crosses over the other toes; and partial fusion (syndactyly) of the second and third toes. Andermann syndrome is associated with a shortened life expectancy, but affected individuals typically live into adulthood. | Andermann syndrome |
How many people are affected by Andermann syndrome ? | Andermann syndrome is most often seen in the French-Canadian population of the Saguenay-Lac-St.-Jean and Charlevoix regions of northeastern Quebec. In this population, Andermann syndrome occurs in almost 1 in 2,000 newborns. Only a few individuals with this disorder have been identified in other regions of the world. | Andermann syndrome |
What are the genetic changes related to Andermann syndrome ? | Mutations in the SLC12A6 gene cause Andermann syndrome. The SLC12A6 gene provides instructions for making a protein called a K-Cl cotransporter. This protein is involved in moving charged atoms (ions) of potassium (K) and chlorine (Cl) across the cell membrane. The positively charged potassium ions and negatively charged chlorine ions are moved together (cotransported), so that the charges inside and outside the cell membrane are unchanged (electroneutral). Electroneutral cotransport of ions across cell membranes is involved in many functions of the body. While the specific function of the K-Cl cotransporter produced from the SLC12A6 gene is unknown, it seems to be critical for the development and maintenance of nerve tissue. It may be involved in regulating the amounts of potassium, chlorine, or water in cells and intercellular spaces. The K-Cl cotransporter protein may also help regulate the activity of other proteins that are sensitive to ion concentrations. Mutations in the SLC12A6 gene that cause Andermann syndrome disrupt the function of the K-Cl cotransporter protein. The lack of functional protein normally produced from the SLC12A6 gene is believed to interfere with the development of the corpus callosum and maintenance of the nerves that transmit signals needed for movement and sensation, resulting in the signs and symptoms of Andermann syndrome. | Andermann syndrome |
Is Andermann 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. | Andermann syndrome |
What are the treatments for Andermann syndrome ? | These resources address the diagnosis or management of Andermann syndrome: - Gene Review: Gene Review: Hereditary Motor and Sensory Neuropathy with Agenesis of the Corpus Callosum - Genetic Testing Registry: Andermann 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 | Andermann syndrome |
What is (are) spondyloepimetaphyseal dysplasia, Strudwick type ? | Spondyloepimetaphyseal dysplasia, Strudwick type is an inherited disorder of bone growth that results in short stature (dwarfism), skeletal abnormalities, and problems with vision. This condition affects the bones of the spine (spondylo-) and two regions (epiphyses and metaphyses) near the ends of long bones in the arms and legs. The Strudwick type was named after the first reported patient with the disorder. People with this condition have short stature from birth, with a very short trunk and shortened limbs. Their hands and feet, however, are usually average-sized. Affected individuals may have an abnormally curved lower back (lordosis) or a spine that curves to the side (scoliosis). This abnormal spinal curvature may be severe and can cause problems with breathing. Instability of the spinal bones (vertebrae) in the neck may increase the risk of spinal cord damage. Other skeletal features include flattened vertebrae (platyspondyly), severe protrusion of the breastbone (pectus carinatum), an abnormality of the hip joint that causes the upper leg bones to turn inward (coxa vara), and an inward- and upward-turning foot (clubfoot). Arthritis may develop early in life. People with spondyloepimetaphyseal dysplasia, Strudwick type have mild changes in their facial features. Some infants are born with an opening in the roof of the mouth (a cleft palate) and their cheekbones may appear flattened. Eye problems that can impair vision are common, such as severe nearsightedness (high myopia) and tearing of the lining of the eye (retinal detachment). | spondyloepimetaphyseal dysplasia, Strudwick type |
How many people are affected by spondyloepimetaphyseal dysplasia, Strudwick type ? | This condition is rare; only a few affected individuals have been reported worldwide. | spondyloepimetaphyseal dysplasia, Strudwick type |
What are the genetic changes related to spondyloepimetaphyseal dysplasia, Strudwick type ? | Spondyloepimetaphyseal dysplasia, Strudwick type is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene. This gene provides instructions for making a protein that forms type II collagen. This type of collagen is found mostly in the clear gel that fills the eyeball (the vitreous) and cartilage. Cartilage is 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. Type II collagen is essential for the normal development of bones and other connective tissues that form the body's supportive framework. Most mutations in the COL2A1 gene that cause spondyloepimetaphyseal dysplasia, Strudwick type interfere with the assembly of type II collagen molecules. Abnormal collagen prevents bones and other connective tissues from developing properly, which leads to the signs and symptoms of spondyloepimetaphyseal dysplasia, Strudwick type. | spondyloepimetaphyseal dysplasia, Strudwick type |
Is spondyloepimetaphyseal dysplasia, Strudwick type 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. | spondyloepimetaphyseal dysplasia, Strudwick type |
What are the treatments for spondyloepimetaphyseal dysplasia, Strudwick type ? | These resources address the diagnosis or management of spondyloepimetaphyseal dysplasia, Strudwick type: - Genetic Testing Registry: Spondyloepimetaphyseal dysplasia Strudwick type - MedlinePlus Encyclopedia: Clubfoot - MedlinePlus Encyclopedia: Retinal Detachment - MedlinePlus Encyclopedia: Scoliosis 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 | spondyloepimetaphyseal dysplasia, Strudwick type |
What is (are) primary spontaneous pneumothorax ? | Primary spontaneous pneumothorax is an abnormal accumulation of air in the space between the lungs and the chest cavity (called the pleural space) that can result in the partial or complete collapse of a lung. This type of pneumothorax is described as primary because it occurs in the absence of lung disease such as emphysema. Spontaneous means the pneumothorax was not caused by an injury such as a rib fracture. Primary spontaneous pneumothorax is likely due to the formation of small sacs of air (blebs) in lung tissue that rupture, causing air to leak into the pleural space. Air in the pleural space creates pressure on the lung and can lead to its collapse. A person with this condition may feel chest pain on the side of the collapsed lung and shortness of breath. Blebs may be present on an individual's lung (or lungs) for a long time before they rupture. Many things can cause a bleb to rupture, such as changes in air pressure or a very sudden deep breath. Often, people who experience a primary spontaneous pneumothorax have no prior sign of illness; the blebs themselves typically do not cause any symptoms and are visible only on medical imaging. Affected individuals may have one bleb to more than thirty blebs. Once a bleb ruptures and causes a pneumothorax, there is an estimated 13 to 60 percent chance that the condition will recur. | primary spontaneous pneumothorax |
How many people are affected by primary spontaneous pneumothorax ? | Primary spontaneous pneumothorax is more common in men than in women. This condition occurs in 7.4 to 18 per 100,000 men each year and 1.2 to 6 per 100,000 women each year. | primary spontaneous pneumothorax |
What are the genetic changes related to primary spontaneous pneumothorax ? | Mutations in the FLCN gene can cause primary spontaneous pneumothorax, although these mutations appear to be a very rare cause of this condition. The FLCN gene provides instructions for making a protein called folliculin. In the lungs, folliculin is found in the connective tissue cells that allow the lungs to contract and expand when breathing. Folliculin is also produced in cells that line the small air sacs (alveoli). Researchers have not determined the protein's function, but they believe it may help control the growth and division of cells. Folliculin may play a role in repairing and re-forming lung tissue following damage. Researchers have not determined how FLCN gene mutations lead to the formation of blebs and increase the risk of primary spontaneous pneumothorax. One theory is that the altered folliculin protein may trigger inflammation within the lung tissue that could alter and damage the tissue, causing blebs. Primary spontaneous pneumothorax most often occurs in people without an identified gene mutation. The cause of the condition in these individuals is often unknown. Tall young men are at increased risk of developing primary spontaneous pneumothorax; researchers suggest that rapid growth of the chest during growth spurts may increase the likelihood of forming blebs. Smoking can also contribute to the development of primary spontaneous pneumothorax. | primary spontaneous pneumothorax |
Is primary spontaneous pneumothorax inherited ? | When this condition is caused by mutations in the FLCN gene, it 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 cases, a person inherits the FLCN gene mutation from an affected parent. People who have an FLCN gene mutation associated with primary spontaneous pneumothorax all appear to develop blebs, but it is estimated that only 40 percent of those individuals go on to have a primary spontaneous pneumothorax. | primary spontaneous pneumothorax |
What are the treatments for primary spontaneous pneumothorax ? | These resources address the diagnosis or management of primary spontaneous pneumothorax: - Genetic Testing Registry: Pneumothorax, primary spontaneous - MedlinePlus Encyclopedia: Chest Tube Insertion - MedlinePlus Encyclopedia: Collapsed Lung - Merck Manual for Patients and Caregivers 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 | primary spontaneous pneumothorax |
What is (are) aniridia ? | Aniridia is an eye disorder characterized by a complete or partial absence of the colored part of the eye (the iris). These iris abnormalities may cause the pupils to be abnormal or misshapen. Aniridia can cause reduction in the sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). People with aniridia can also have other eye problems. Increased pressure in the eye (glaucoma) typically appears in late childhood or early adolescence. Clouding of the lens of the eye (cataracts), occur in 50 percent to 85 percent of people with aniridia. In about 10 percent of affected people, the structures that carry information from the eyes to the brain (optic nerves) are underdeveloped. Individuals with aniridia may also have involuntary eye movements (nystagmus) or underdevelopment of the region at the back of the eye responsible for sharp central vision (foveal hypoplasia). Many of these eye problems contribute to progressive vision loss in affected individuals. The severity of symptoms is typically the same in both eyes. Rarely, people with aniridia have behavioral problems, developmental delay, and problems detecting odors. | aniridia |
How many people are affected by aniridia ? | Aniridia occurs in 1 in 50,000 to 100,000 newborns worldwide. | aniridia |
What are the genetic changes related to aniridia ? | Aniridia is caused by mutations in the PAX6 gene. The PAX6 gene provides instructions for making a protein that is involved in the early development of the eyes, brain and spinal cord (central nervous system), and the pancreas. Within the brain, the PAX6 protein is involved in the development of a specialized group of brain cells that process smell (the olfactory bulb). The PAX6 protein attaches (binds) to specific regions of DNA and regulates the activity of other genes. On the basis of this role, the PAX6 protein is called a transcription factor. Following birth, the PAX6 protein regulates several genes that likely contribute to the maintenance of different eye structures. Mutations in the PAX6 gene result in the production of a nonfunctional PAX6 protein that is unable to bind to DNA and regulate the activity of other genes. A lack of functional PAX6 protein disrupts the formation of the eyes during embryonic development. | aniridia |
Is aniridia inherited ? | Aniridia 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 approximately two-thirds of cases, an affected person inherits the mutation from one affected parent. The remaining one-third of cases result from new mutations in the gene and occur in people with no history of the disorder in their family. | aniridia |
What are the treatments for aniridia ? | These resources address the diagnosis or management of aniridia: - Gene Review: Gene Review: Aniridia - Genetic Testing Registry: Congenital aniridia 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 | aniridia |
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