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What is (are) spastic paraplegia type 8 ? | Spastic paraplegia type 8 is part of a group of genetic disorders known as hereditary spastic paraplegias. These disorders are characterized by progressive muscle stiffness (spasticity) and the development of paralysis of the lower limbs (paraplegia). Hereditary spastic paraplegias are divided into two types: pure and complex. The pure types involve only the nerves and muscles controlling the lower limbs and bladder, whereas the complex types also have significant involvement of the nervous system in other parts of the body. Spastic paraplegia type 8 is a pure hereditary spastic paraplegia. Like all hereditary spastic paraplegias, spastic paraplegia type 8 involves spasticity of the leg muscles and muscle weakness. People with this condition can also experience exaggerated reflexes (hyperreflexia), a decreased ability to feel vibrations, muscle wasting (amyotrophy), and reduced bladder control. The signs and symptoms of spastic paraplegia type 8 usually appear in early to mid-adulthood. As the muscle weakness and spasticity get worse, some people may need the aid of a cane, walker, or wheelchair. | spastic paraplegia type 8 |
How many people are affected by spastic paraplegia type 8 ? | The prevalence of all hereditary spastic paraplegias combined is estimated to be 1 to 18 in 100,000 people worldwide. Spastic paraplegia type 8 likely accounts for only a small percentage of all spastic paraplegia cases. | spastic paraplegia type 8 |
What are the genetic changes related to spastic paraplegia type 8 ? | Mutations in the KIAA0196 gene cause spastic paraplegia type 8. The KIAA0196 gene provides instructions for making a protein called strumpellin. Strumpellin is active (expressed) throughout the body, although its exact function is unknown. The protein's structure suggests that strumpellin may interact with the structural framework inside cells (the cytoskeleton) and may attach (bind) to other proteins. KIAA0196 gene mutations are thought to change the structure of the strumpellin protein. It is unknown how the altered strumpellin protein causes the signs and symptoms of spastic paraplegia type 8. | spastic paraplegia type 8 |
Is spastic paraplegia type 8 inherited ? | Spastic paraplegia type 8 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, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family. | spastic paraplegia type 8 |
What are the treatments for spastic paraplegia type 8 ? | These resources address the diagnosis or management of spastic paraplegia type 8: - Gene Review: Gene Review: Spastic Paraplegia 8 - Genetic Testing Registry: Spastic paraplegia 8 - Spastic Paraplegia Foundation, Inc.: Treatments and Therapies These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | spastic paraplegia type 8 |
What is (are) arginase deficiency ? | Arginase deficiency is an inherited disorder that causes the amino acid arginine (a building block of proteins) and ammonia to accumulate gradually in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if levels become too high. The nervous system is especially sensitive to the effects of excess ammonia. Arginase deficiency usually becomes evident by about the age of 3. It most often appears as stiffness, especially in the legs, caused by abnormal tensing of the muscles (spasticity). Other symptoms may include slower than normal growth, developmental delay and eventual loss of developmental milestones, intellectual disability, seizures, tremor, and difficulty with balance and coordination (ataxia). Occasionally, high protein meals or stress caused by illness or periods without food (fasting) may cause ammonia to accumulate more quickly in the blood. This rapid increase in ammonia may lead to episodes of irritability, refusal to eat, and vomiting. In some affected individuals, signs and symptoms of arginase deficiency may be less severe, and may not appear until later in life. | arginase deficiency |
How many people are affected by arginase deficiency ? | Arginase deficiency is a very rare disorder; it has been estimated to occur once in every 300,000 to 1,000,000 individuals. | arginase deficiency |
What are the genetic changes related to arginase deficiency ? | Mutations in the ARG1 gene cause arginase deficiency. Arginase deficiency belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of reactions that occurs in liver cells. This cycle processes excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys. The ARG1 gene provides instructions for making an enzyme called arginase. This enzyme controls the final step of the urea cycle, which produces urea by removing nitrogen from arginine. In people with arginase deficiency, arginase is damaged or missing, and arginine is not broken down properly. As a result, urea cannot be produced normally, and excess nitrogen accumulates in the blood in the form of ammonia. The accumulation of ammonia and arginine are believed to cause the neurological problems and other signs and symptoms of arginase deficiency. | arginase deficiency |
Is arginase 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. | arginase deficiency |
What are the treatments for arginase deficiency ? | These resources address the diagnosis or management of arginase deficiency: - Baby's First Test - Gene Review: Gene Review: Arginase Deficiency - Gene Review: Gene Review: Urea Cycle Disorders Overview - Genetic Testing Registry: Arginase deficiency - MedlinePlus Encyclopedia: Hereditary urea cycle abnormality These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | arginase deficiency |
What is (are) primary sclerosing cholangitis ? | Primary sclerosing cholangitis is a condition that affects the bile ducts. These ducts carry bile (a fluid that helps to digest fats) from the liver, where bile is produced, to the gallbladder, where it is stored, and to the small intestine, where it aids in digestion. Primary sclerosing cholangitis occurs because of inflammation in the bile ducts (cholangitis) that leads to scarring (sclerosis) and narrowing of the ducts. As a result, bile cannot be released to the gallbladder and small intestine, and it builds up in the liver. Primary sclerosing cholangitis is usually diagnosed around age 40, and for unknown reasons, it affects men twice as often as women. Many people have no signs or symptoms of the condition when they are diagnosed, but routine blood tests reveal liver problems. When apparent, the earliest signs and symptoms of primary sclerosing cholangitis include extreme tiredness (fatigue), discomfort in the abdomen, and severe itchiness (pruritus). As the condition worsens, affected individuals may develop yellowing of the skin and whites of the eyes (jaundice) and an enlarged spleen (splenomegaly). Eventually, the buildup of bile damages the liver cells, causing chronic liver disease (cirrhosis) and liver failure. Without bile available to digest them, fats pass through the body. As a result, weight loss and shortages of vitamins that are absorbed with and stored in fats (fat-soluble vitamins) can occur. A fat-soluble vitamin called vitamin D helps absorb calcium and helps bones harden, and lack of this vitamin can cause thinning of the bones (osteoporosis) in people with primary sclerosing cholangitis. Primary sclerosing cholangitis is often associated with another condition called inflammatory bowel disease, which is characterized by inflammation of the intestines that causes open sores (ulcers) in the intestines and abdominal pain. However, the reason for this link is unclear. Approximately 70 percent of people with primary sclerosing cholangitis have inflammatory bowel disease, most commonly a form of the condition known as ulcerative colitis. In addition, people with primary sclerosing cholangitis are more likely to have an autoimmune disorder, such as type 1 diabetes, celiac disease, or thyroid disease, than people without the condition. Autoimmune disorders occur when the immune system malfunctions and attacks the body's tissues and organs. People with primary sclerosing cholangitis also have an increased risk of developing cancer, particularly cancer of the bile ducts (cholangiocarcinoma). | primary sclerosing cholangitis |
How many people are affected by primary sclerosing cholangitis ? | An estimated 1 in 10,000 people have primary sclerosing cholangitis, and the condition is diagnosed in approximately 1 in 100,000 people per year worldwide. | primary sclerosing cholangitis |
What are the genetic changes related to primary sclerosing cholangitis ? | Primary sclerosing cholangitis is thought to arise from a combination of genetic and environmental factors. Researchers believe that genetic changes play a role in this condition because it often occurs in several members of a family and because immediate family members of someone with primary sclerosing cholangitis have an increased risk of developing the condition. It is likely that specific genetic variations increase a person's risk of developing primary sclerosing cholangitis, and then exposure to certain environmental factors triggers the disorder. However, the genetic changes that increase susceptibility and the environmental triggers remain unclear. There is evidence that variations in certain genes involved in immune function influence the risk of developing primary sclerosing cholangitis. The most commonly associated genes belong to a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders (such as viruses and bacteria). Each HLA gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign proteins. Specific variations of several HLA genes seem to be present more often in people with primary sclerosing cholangitis than in people who do not have the disorder. These variations may dysregulate the body's immune response, leading to the inflammation of the bile ducts in people with primary sclerosing cholangitis. However, the mechanism is not well understood. Researchers are also studying variations in other genes related to the body's immune function to understand how they contribute to the risk of developing this condition. | primary sclerosing cholangitis |
Is primary sclerosing cholangitis inherited ? | The inheritance pattern of primary sclerosing cholangitis is unknown because many genetic and environmental factors are likely to be involved. This condition tends to cluster in families, however, and having an affected family member is a risk factor for developing the disease. | primary sclerosing cholangitis |
What are the treatments for primary sclerosing cholangitis ? | These resources address the diagnosis or management of primary sclerosing cholangitis: - American Liver Foundation: Primary Sclerosing Cholangitis (PSC) - Genetic Testing Registry: Primary sclerosing cholangitis - MedlinePlus Encyclopedia: Sclerosing Cholangitis - University of California San Francisco Medical 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 | primary sclerosing cholangitis |
What is (are) Snyder-Robinson syndrome ? | Snyder-Robinson syndrome is a condition characterized by intellectual disability, muscle and bone abnormalities, and other problems with development. It occurs exclusively in males. Males with Snyder-Robinson syndrome have delayed development and intellectual disability beginning in early childhood. The intellectual disability can range from mild to profound. Speech often develops late, and speech difficulties are common. Some affected individuals never develop any speech. Most affected males are thin and have low muscle mass, a body type described as an asthenic habitus. Weakness or "floppiness" (hypotonia) typically becomes apparent in infancy, and the loss of muscle tissue continues with age. People with this condition often have difficulty walking; most have an unsteady gait. Snyder-Robinson syndrome causes skeletal problems, particularly thinning of the bones (osteoporosis) that starts in early childhood. Osteoporosis causes the bones to be brittle and to break easily, often during normal activities. In people with Snyder-Robinson syndrome, broken bones occur most often in the arms and legs. Most affected individuals also develop an abnormal side-to-side and back-to-front curvature of the spine (scoliosis and kyphosis, often called kyphoscoliosis when they occur together). Affected individuals tend to be shorter than their peers and others in their family. Snyder-Robinson syndrome is associated with distinctive facial features, including a prominent lower lip; a high, narrow roof of the mouth or an opening in the roof of the mouth (a cleft palate); and differences in the size and shape of the right and left sides of the face (facial asymmetry). Other signs and symptoms that have been reported include seizures that begin in childhood and abnormalities of the genitalia and kidneys. | Snyder-Robinson syndrome |
How many people are affected by Snyder-Robinson syndrome ? | Snyder-Robinson syndrome is a rare condition; its prevalence is unknown. About 10 affected families have been identified worldwide. | Snyder-Robinson syndrome |
What are the genetic changes related to Snyder-Robinson syndrome ? | Snyder-Robinson syndrome results from mutations in the SMS gene. This gene provides instructions for making an enzyme called spermine synthase. This enzyme is involved in the production of spermine, which is a type of small molecule called a polyamine. Polyamines have many critical functions within cells. Studies suggest that these molecules play roles in cell growth and division, the production of new proteins, the repair of damaged tissues, the function of molecules called ion channels, and the controlled self-destruction of cells (apoptosis). Polyamines appear to be necessary for normal development and function of the brain and other parts of the body. Mutations in the SMS gene greatly reduce or eliminate the activity of spermine synthase, which decreases the amount of spermine in cells. A shortage of this polyamine clearly impacts normal development, including the development of the brain, muscles, and bones, but it is unknown how it leads to the specific signs and symptoms of Snyder-Robinson syndrome. | Snyder-Robinson syndrome |
Is Snyder-Robinson syndrome inherited ? | This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. No cases of Snyder-Robinson syndrome in females have been reported. | Snyder-Robinson syndrome |
What are the treatments for Snyder-Robinson syndrome ? | These resources address the diagnosis or management of Snyder-Robinson syndrome: - Gene Review: Gene Review: Snyder-Robinson Syndrome - Genetic Testing Registry: Snyder Robinson 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 | Snyder-Robinson syndrome |
What is (are) Townes-Brocks Syndrome ? | Townes-Brocks syndrome is a genetic condition that affects several parts of the body. The most common features of this condition are an obstruction of the anal opening (imperforate anus), abnormally shaped ears, and hand malformations that most often affect the thumb. Most people with this condition have at least two of these three major features. Other possible signs and symptoms of Townes-Brocks syndrome include kidney abnormalities, mild to profound hearing loss, heart defects, and genital malformations. These features vary among affected individuals, even within the same family. Intellectual disability or learning problems have also been reported in about 10 percent of people with Townes-Brocks syndrome. | Townes-Brocks Syndrome |
How many people are affected by Townes-Brocks Syndrome ? | The prevalence of this condition is unknown, although one study estimated that it may affect 1 in 250,000 people. It is difficult to determine how frequently Townes-Brocks syndrome occurs because the varied signs and symptoms of this disorder overlap with those of other genetic syndromes. | Townes-Brocks Syndrome |
What are the genetic changes related to Townes-Brocks Syndrome ? | Mutations in the SALL1 gene cause Townes-Brocks Syndrome. The SALL1 gene is part of a group of genes called the SALL family. These genes provide instructions for making proteins that are involved in the formation of tissues and organs before birth. SALL proteins act as transcription factors, which means they attach (bind) to specific regions of DNA and help control the activity of particular genes. Some mutations in the SALL1 gene lead to the production of an abnormally short version of the SALL1 protein that malfunctions within the cell. Other mutations prevent one copy of the gene in each cell from making any protein. It is unclear how these genetic changes disrupt normal development and cause the birth defects associated with Townes-Brocks syndrome. | Townes-Brocks Syndrome |
Is Townes-Brocks Syndrome inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. | Townes-Brocks Syndrome |
What are the treatments for Townes-Brocks Syndrome ? | These resources address the diagnosis or management of Townes-Brocks Syndrome: - Gene Review: Gene Review: Townes-Brocks Syndrome - Genetic Testing Registry: Townes syndrome - MedlinePlus Encyclopedia: Ear Disorders (image) - MedlinePlus Encyclopedia: Imperforate Anus These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Townes-Brocks Syndrome |
What is (are) Potocki-Shaffer syndrome ? | Potocki-Shaffer syndrome is a disorder that affects development of the bones, nerve cells in the brain, and other tissues. Most people with this condition have multiple noncancerous (benign) bone tumors called osteochondromas. In rare instances, these tumors become cancerous. People with Potocki-Shaffer syndrome also have enlarged openings in the two bones that make up much of the top and sides of the skull (enlarged parietal foramina). These abnormal openings form extra "soft spots" on the head, in addition to the two that newborns normally have. Unlike the usual newborn soft spots, the enlarged parietal foramina remain open throughout life. The signs and symptoms of Potocki-Shaffer syndrome vary widely. In addition to multiple osteochondromas and enlarged parietal foramina, affected individuals often have intellectual disability and delayed development of speech, motor skills (such as sitting and walking), and social skills. Many people with this condition have distinctive facial features, which can include a wide, short skull (brachycephaly); a prominent forehead; a narrow bridge of the nose; a shortened distance between the nose and upper lip (a short philtrum); and a downturned mouth. Less commonly, Potocki-Shaffer syndrome causes vision problems, additional skeletal abnormalities, and defects in the heart, kidneys, and urinary tract. | Potocki-Shaffer syndrome |
How many people are affected by Potocki-Shaffer syndrome ? | Potocki-Shaffer syndrome is a rare condition, although its prevalence is unknown. Fewer than 100 cases have been reported in the scientific literature. | Potocki-Shaffer syndrome |
What are the genetic changes related to Potocki-Shaffer syndrome ? | Potocki-Shaffer syndrome (also known as proximal 11p deletion syndrome) is caused by a deletion of genetic material from the short (p) arm of chromosome 11 at a position designated 11p11.2. The size of the deletion varies among affected individuals. Studies suggest that the full spectrum of features is caused by a deletion of at least 2.1 million DNA building blocks (base pairs), also written as 2.1 megabases (Mb). The loss of multiple genes within the deleted region causes the varied signs and symptoms of Potocki-Shaffer syndrome. In particular, deletion of the EXT2, ALX4, and PHF21A genes are associated with several of the characteristic features of Potocki-Shaffer syndrome. Research shows that loss of the EXT2 gene is associated with the development of multiple osteochondromas in affected individuals. Deletion of another gene, ALX4, causes the enlarged parietal foramina found in people with this condition. In addition, loss of the PHF21A gene is the cause of intellectual disability and distinctive facial features in many people with the condition. The loss of additional genes in the deleted region likely contributes to the other features of Potocki-Shaffer syndrome. | Potocki-Shaffer syndrome |
Is Potocki-Shaffer syndrome inherited ? | Potocki-Shaffer syndrome follows an autosomal dominant inheritance pattern, which means a deletion of genetic material from one copy of chromosome 11 is sufficient to cause the disorder. In some cases, an affected person inherits the chromosome with a deleted segment from an affected parent. More commonly, the condition results from a deletion that occurs during the formation of reproductive cells (eggs and sperm) in a parent or in early fetal development. These cases occur in people with no history of the disorder in their family. | Potocki-Shaffer syndrome |
What are the treatments for Potocki-Shaffer syndrome ? | These resources address the diagnosis or management of Potocki-Shaffer syndrome: - Genetic Testing Registry: Potocki-Shaffer 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 | Potocki-Shaffer syndrome |
What is (are) tyrosinemia ? | Tyrosinemia is a genetic disorder characterized by disruptions in the multistep process that breaks down the amino acid tyrosine, a building block of most proteins. If untreated, tyrosine and its byproducts build up in tissues and organs, which can lead to serious health problems. There are three types of tyrosinemia, which are each distinguished by their symptoms and genetic cause. Tyrosinemia type I, the most severe form of this disorder, is characterized by signs and symptoms that begin in the first few months of life. Affected infants fail to gain weight and grow at the expected rate (failure to thrive) due to poor food tolerance because high-protein foods lead to diarrhea and vomiting. Affected infants may also have yellowing of the skin and whites of the eyes (jaundice), a cabbage-like odor, and an increased tendency to bleed (particularly nosebleeds). Tyrosinemia type I can lead to liver and kidney failure, softening and weakening of the bones (rickets), and an increased risk of liver cancer (hepatocellular carcinoma). Some affected children have repeated neurologic crises that consist of changes in mental state, reduced sensation in the arms and legs (peripheral neuropathy), abdominal pain, and respiratory failure. These crises can last from 1 to 7 days. Untreated, children with tyrosinemia type I often do not survive past the age of 10. Tyrosinemia type II can affect the eyes, skin, and mental development. Signs and symptoms often begin in early childhood and include eye pain and redness, excessive tearing, abnormal sensitivity to light (photophobia), and thick, painful skin on the palms of their hands and soles of their feet (palmoplantar hyperkeratosis). About 50 percent of individuals with tyrosinemia type II have some degree of intellectual disability. Tyrosinemia type III is the rarest of the three types. The characteristic features of this type include intellectual disability, seizures, and periodic loss of balance and coordination (intermittent ataxia). About 10 percent of newborns have temporarily elevated levels of tyrosine (transient tyrosinemia). In these cases, the cause is not genetic. The most likely causes are vitamin C deficiency or immature liver enzymes due to premature birth. | tyrosinemia |
How many people are affected by tyrosinemia ? | Worldwide, tyrosinemia type I affects about 1 in 100,000 individuals. This type is more common in Norway where 1 in 60,000 to 74,000 individuals are affected. Tyrosinemia type I is even more common in Quebec, Canada where it occurs in about 1 in 16,000 individuals. In the Saguenay-Lac St. Jean region of Quebec, tyrosinemia type I affects 1 in 1,846 people. Tyrosinemia type II occurs in fewer than 1 in 250,000 individuals worldwide. Tyrosinemia type III is very rare; only a few cases have been reported. | tyrosinemia |
What are the genetic changes related to tyrosinemia ? | Mutations in the FAH, TAT, and HPD genes can cause tyrosinemia types I, II, and III, respectively. In the liver, enzymes break down tyrosine in a five step process, resulting in molecules that are either excreted by the kidneys or used to produce energy or make other substances in the body. The FAH gene provides instructions for the fumarylacetoacetate hydrolase enzyme, which is responsible for the final step of tyrosine breakdown. The enzyme produced from the TAT gene, called tyrosine aminotransferase enzyme, is involved at the first step in the process. The HPD gene provides instructions for making the 4-hydroxyphenylpyruvate dioxygenase enzyme, which is responsible for the second step. Mutations in the FAH, TAT, or HPD gene cause a decrease in the activity of one of the enzymes in the breakdown of tyrosine. As a result, tyrosine and its byproducts accumulate to toxic levels, which can cause damage and death to cells in the liver, kidneys, nervous system, and other organs. | tyrosinemia |
Is tyrosinemia 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. | tyrosinemia |
What are the treatments for tyrosinemia ? | These resources address the diagnosis or management of tyrosinemia: - Baby's First Test: Tyrosinemia, Type I - Baby's First Test: Tyrosinemia, Type II - Baby's First Test: Tyrosinemia, Type III - Gene Review: Gene Review: Tyrosinemia Type I - Genetic Testing Registry: 4-Hydroxyphenylpyruvate dioxygenase deficiency - Genetic Testing Registry: Tyrosinemia type 2 - Genetic Testing Registry: Tyrosinemia type I - MedlinePlus Encyclopedia: Aminoaciduria 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 | tyrosinemia |
What is (are) Angelman syndrome ? | Angelman syndrome is a complex genetic disorder that primarily affects the nervous system. Characteristic features of this condition include delayed development, intellectual disability, severe speech impairment, and problems with movement and balance (ataxia). Most affected children also have recurrent seizures (epilepsy) and a small head size (microcephaly). Delayed development becomes noticeable by the age of 6 to 12 months, and other common signs and symptoms usually appear in early childhood. Children with Angelman syndrome typically have a happy, excitable demeanor with frequent smiling, laughter, and hand-flapping movements. Hyperactivity, a short attention span, and a fascination with water are common. Most affected children also have difficulty sleeping and need less sleep than usual. With age, people with Angelman syndrome become less excitable, and the sleeping problems tend to improve. However, affected individuals continue to have intellectual disability, severe speech impairment, and seizures throughout their lives. Adults with Angelman syndrome have distinctive facial features that may be described as "coarse." Other common features include unusually fair skin with light-colored hair and an abnormal side-to-side curvature of the spine (scoliosis). The life expectancy of people with this condition appears to be nearly normal. | Angelman syndrome |
How many people are affected by Angelman syndrome ? | Angelman syndrome affects an estimated 1 in 12,000 to 20,000 people. | Angelman syndrome |
What are the genetic changes related to Angelman syndrome ? | Many of the characteristic features of Angelman syndrome result from the loss of function of a gene called UBE3A. People normally inherit one copy of the UBE3A gene from each parent. Both copies of this gene are turned on (active) in many of the body's tissues. In certain areas of the brain, however, only the copy inherited from a person's mother (the maternal copy) is active. This parent-specific gene activation is caused by a phenomenon called genomic imprinting. If the maternal copy of the UBE3A gene is lost because of a chromosomal change or a gene mutation, a person will have no active copies of the gene in some parts of the brain. Several different genetic mechanisms can inactivate or delete the maternal copy of the UBE3A gene. Most cases of Angelman syndrome (about 70 percent) occur when a segment of the maternal chromosome 15 containing this gene is deleted. In other cases (about 11 percent), Angelman syndrome is caused by a mutation in the maternal copy of the UBE3A gene. In a small percentage of cases, Angelman syndrome results when a person inherits two copies of chromosome 15 from his or her father (paternal copies) instead of one copy from each parent. This phenomenon is called paternal uniparental disomy. Rarely, Angelman syndrome can also be caused by a chromosomal rearrangement called a translocation, or by a mutation or other defect in the region of DNA that controls activation of the UBE3A gene. These genetic changes can abnormally turn off (inactivate) UBE3A or other genes on the maternal copy of chromosome 15. The causes of Angelman syndrome are unknown in 10 to 15 percent of affected individuals. Changes involving other genes or chromosomes may be responsible for the disorder in these cases. In some people who have Angelman syndrome, the loss of a gene called OCA2 is associated with light-colored hair and fair skin. The OCA2 gene is located on the segment of chromosome 15 that is often deleted in people with this disorder. However, loss of the OCA2 gene does not cause the other signs and symptoms of Angelman syndrome. The protein produced from this gene helps determine the coloring (pigmentation) of the skin, hair, and eyes. | Angelman syndrome |
Is Angelman syndrome inherited ? | Most cases of Angelman syndrome are not inherited, particularly those caused by a deletion in the maternal chromosome 15 or by paternal uniparental disomy. These genetic changes occur as random events during the formation of reproductive cells (eggs and sperm) or in early embryonic development. Affected people typically have no history of the disorder in their family. Rarely, a genetic change responsible for Angelman syndrome can be inherited. For example, it is possible for a mutation in the UBE3A gene or in the nearby region of DNA that controls gene activation to be passed from one generation to the next. | Angelman syndrome |
What are the treatments for Angelman syndrome ? | These resources address the diagnosis or management of Angelman syndrome: - Gene Review: Gene Review: Angelman Syndrome - Genetic Testing Registry: Angelman syndrome - MedlinePlus Encyclopedia: Speech Disorders 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 | Angelman syndrome |
What is (are) deafness-dystonia-optic neuronopathy syndrome ? | Deafness-dystonia-optic neuronopathy (DDON) syndrome, also known as Mohr-Tranebjrg syndrome, is characterized by hearing loss that begins early in life, problems with movement, impaired vision, and behavior problems. This condition occurs almost exclusively in males. The first symptom of DDON syndrome is hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss), which begins in early childhood. The hearing impairment worsens over time, and most affected individuals have profound hearing loss by age 10. People with DDON syndrome typically begin to develop problems with movement during their teens, although the onset of these symptoms varies among affected individuals. Some people experience involuntary tensing of the muscles (dystonia), while others have difficulty coordinating movements (ataxia). The problems with movement usually worsen over time. Individuals with DDON syndrome have normal vision during childhood, but they may begin to develop an increased sensitivity to light (photophobia) or other vision problems during their teens. These people often have a slowly progressive reduction in the sharpness of vision (visual acuity) and become legally blind in mid-adulthood. People with this condition may also have behavior problems, including changes in personality and aggressive or paranoid behaviors. They also usually develop a gradual decline in thinking and reasoning abilities (dementia) in their forties. The lifespan of individuals with DDON syndrome depends on the severity of the disorder. People with severe cases have survived into their teenage years, while those with milder cases have lived into their sixties. | deafness-dystonia-optic neuronopathy syndrome |
How many people are affected by deafness-dystonia-optic neuronopathy syndrome ? | DDON syndrome is a rare disorder; it has been reported in fewer than 70 people worldwide. | deafness-dystonia-optic neuronopathy syndrome |
What are the genetic changes related to deafness-dystonia-optic neuronopathy syndrome ? | Mutations in the TIMM8A gene cause DDON syndrome. The protein produced from this gene is found inside the energy-producing centers of cells (mitochondria). The TIMM8A protein forms a complex (a group of proteins that work together) with a very similar protein called TIMM13. This complex functions by transporting other proteins within the mitochondria. Most mutations in the TIMM8A gene result in the absence of functional TIMM8A protein inside the mitochondria, which prevents the formation of the TIMM8A/TIMM13 complex. Researchers believe that the lack of this complex leads to abnormal protein transport, although it is unclear how abnormal protein transport affects the function of the mitochondria and causes the signs and symptoms of DDON syndrome. | deafness-dystonia-optic neuronopathy syndrome |
Is deafness-dystonia-optic neuronopathy syndrome inherited ? | DDON syndrome is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause DDON syndrome. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. Females who carry one altered copy of the TIMM8A gene are typically unaffected; however, they may develop mild hearing loss and dystonia. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | deafness-dystonia-optic neuronopathy syndrome |
What are the treatments for deafness-dystonia-optic neuronopathy syndrome ? | These resources address the diagnosis or management of deafness-dystonia-optic neuronopathy syndrome: - Gene Review: Gene Review: Deafness-Dystonia-Optic Neuronopathy Syndrome - Genetic Testing Registry: Mohr-Tranebjaerg 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 | deafness-dystonia-optic neuronopathy syndrome |
What is (are) myosin storage myopathy ? | Myosin storage myopathy is a condition that causes muscle weakness (myopathy) that does not worsen or worsens very slowly over time. This condition is characterized by the formation of protein clumps, which contain a protein called myosin, within certain muscle fibers. The signs and symptoms of myosin storage myopathy usually become noticeable in childhood, although they can occur later. Because of muscle weakness, affected individuals may start walking later than usual and have a waddling gait, trouble climbing stairs, and difficulty lifting the arms above shoulder level. Muscle weakness also causes some affected individuals to have trouble breathing. | myosin storage myopathy |
How many people are affected by myosin storage myopathy ? | Myosin storage myopathy is a rare condition. Its prevalence is unknown. | myosin storage myopathy |
What are the genetic changes related to myosin storage myopathy ? | Mutations in the MYH7 gene cause myosin storage myopathy. The MYH7 gene provides instructions for making a protein known as the cardiac beta ()-myosin heavy chain. This protein is found in heart (cardiac) muscle and in type I skeletal muscle fibers, one of two types of fibers that make up the muscles that the body uses for movement. Cardiac -myosin heavy chain is the major component of the thick filament in muscle cell structures called sarcomeres. Sarcomeres, which are made up of thick and thin filaments, are the basic units of muscle contraction. The overlapping thick and thin filaments attach to each other and release, which allows the filaments to move relative to one another so that muscles can contract. Mutations in the MYH7 gene lead to the production of an altered cardiac -myosin heavy chain protein, which is thought to be less able to form thick filaments. The altered proteins accumulate in type I skeletal muscle fibers, forming the protein clumps characteristic of the disorder. It is unclear how these changes lead to muscle weakness in people with myosin storage myopathy. | myosin storage myopathy |
Is myosin storage myopathy 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. | myosin storage myopathy |
What are the treatments for myosin storage myopathy ? | These resources address the diagnosis or management of myosin storage myopathy: - Genetic Testing Registry: Myosin storage myopathy 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 | myosin storage myopathy |
What is (are) Troyer syndrome ? | Troyer syndrome is part of a group of genetic disorders known as hereditary spastic paraplegias. These disorders are characterized by progressive muscle stiffness (spasticity) and the development of paralysis of the lower limbs (paraplegia). Hereditary spastic paraplegias are divided into two types: pure and complex. The pure types involve the lower limbs. The complex types involve the lower limbs and can also affect the upper limbs to a lesser degree; the structure or functioning of the brain; and the nerves connecting the brain and spinal cord to muscles and sensory cells that detect sensations such as touch, pain, heat, and sound (the peripheral nervous system). Troyer syndrome is a complex hereditary spastic paraplegia. People with Troyer syndrome can experience a variety of signs and symptoms. The most common characteristics of Troyer syndrome are spasticity of the leg muscles, progressive muscle weakness, paraplegia, muscle wasting in the hands and feet (distal amyotrophy), small stature, developmental delay, learning disorders, speech difficulties (dysarthria), and mood swings. Other characteristics can include exaggerated reflexes (hyperreflexia) in the lower limbs, uncontrollable movements of the limbs (choreoathetosis), skeletal abnormalities, and a bending outward (valgus) of the knees. Troyer syndrome causes the degeneration and death of muscle cells and motor neurons (specialized nerve cells that control muscle movement) throughout a person's lifetime, leading to a slow progressive decline in muscle and nerve function. The severity of impairment related to Troyer syndrome increases as a person ages. Most affected individuals require a wheelchair by the time they are in their fifties or sixties. | Troyer syndrome |
How many people are affected by Troyer syndrome ? | About 20 cases of Troyer syndrome have been reported in the Old Order Amish population of Ohio. It has not been found outside this population. | Troyer syndrome |
What are the genetic changes related to Troyer syndrome ? | Troyer syndrome is caused by a mutation in the SPG20 gene. The SPG20 gene provides instructions for producing a protein called spartin, whose function is not entirely understood. Researchers believe that spartin may be involved in a variety of cell functions, from breaking down proteins to transporting materials from the cell surface into the cell (endocytosis). Spartin is found in a wide range of body tissues, including the nervous system. | Troyer syndrome |
Is Troyer 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. | Troyer syndrome |
What are the treatments for Troyer syndrome ? | These resources address the diagnosis or management of Troyer syndrome: - Gene Review: Gene Review: Hereditary Spastic Paraplegia Overview - Gene Review: Gene Review: Troyer Syndrome - Genetic Testing Registry: Troyer syndrome - Spastic Paraplegia Foundation, Inc.: Treatments and Therapies These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Troyer syndrome |
What is (are) Wolf-Hirschhorn syndrome ? | Wolf-Hirschhorn syndrome is a condition that affects many parts of the body. The major features of this disorder include a characteristic facial appearance, delayed growth and development, intellectual disability, and seizures. Almost everyone with this disorder has distinctive facial features, including a broad, flat nasal bridge and a high forehead. This combination is described as a "Greek warrior helmet" appearance. The eyes are widely spaced and may be protruding. Other characteristic facial features include a shortened distance between the nose and upper lip (a short philtrum), a downturned mouth, a small chin (micrognathia), and poorly formed ears with small holes (pits) or flaps of skin (tags). Additionally, affected individuals may have asymmetrical facial features and an unusually small head (microcephaly). People with Wolf-Hirschhorn syndrome experience delayed growth and development. Slow growth begins before birth, and affected infants tend to have problems feeding and gaining weight (failure to thrive). They also have weak muscle tone (hypotonia) and underdeveloped muscles. Motor skills such as sitting, standing, and walking are significantly delayed. Most children and adults with this disorder also have short stature. Intellectual disability ranges from mild to severe in people with Wolf-Hirschhorn syndrome. Compared to people with other forms of intellectual disability, their socialization skills are strong, while verbal communication and language skills tend to be weaker. Most affected children also have seizures, which may be resistant to treatment. Seizures tend to disappear with age. Additional features of Wolf-Hirschhorn syndrome include skin changes such as mottled or dry skin, skeletal abnormalities such as abnormal curvature of the spine (scoliosis and kyphosis), dental problems including missing teeth, and an opening in the roof of the mouth (cleft palate) and/or in the lip (cleft lip). Wolf-Hirschhorn syndrome can also cause abnormalities of the eyes, heart, genitourinary tract, and brain. A condition called Pitt-Rogers-Danks syndrome has features that overlap with those of Wolf-Hirschhorn syndrome. Researchers now recognize that these two conditions are actually part of a single syndrome with variable signs and symptoms. | Wolf-Hirschhorn syndrome |
How many people are affected by Wolf-Hirschhorn syndrome ? | The prevalence of Wolf-Hirschhorn syndrome is estimated to be 1 in 50,000 births. However, this may be an underestimate because it is likely that some affected individuals are never diagnosed. For unknown reasons, Wolf-Hirschhorn syndrome occurs in about twice as many females as males. | Wolf-Hirschhorn syndrome |
What are the genetic changes related to Wolf-Hirschhorn syndrome ? | Wolf-Hirschhorn syndrome is caused by a deletion of genetic material near the end of the short (p) arm of chromosome 4. This chromosomal change is sometimes written as 4p-. The size of the deletion varies among affected individuals; studies suggest that larger deletions tend to result in more severe intellectual disability and physical abnormalities than smaller deletions. The signs and symptoms of Wolf-Hirschhorn are related to the loss of multiple genes on the short arm of chromosome 4. WHSC1, LETM1, and MSX1 are the genes that are deleted in people with the typical signs and symptoms of this disorder. These genes play significant roles in early development, although many of their specific functions are unknown. Researchers believe that loss of the WHSC1 gene is associated with many of the characteristic features of Wolf-Hirschhorn syndrome, including the distinctive facial appearance and developmental delay. Deletion of the LETM1 gene appears to be associated with seizures or other abnormal electrical activity in the brain. A loss of the MSX1 gene may be responsible for the dental abnormalities and cleft lip and/or palate that are often seen with this condition. Scientists are working to identify additional genes at the end of the short arm of chromosome 4 that contribute to the characteristic features of Wolf-Hirschhorn syndrome. | Wolf-Hirschhorn syndrome |
Is Wolf-Hirschhorn syndrome inherited ? | Between 85 and 90 percent of all cases of Wolf-Hirschhorn syndrome are not inherited. They result from a chromosomal deletion that occurs as a random (de novo) event during the formation of reproductive cells (eggs or sperm) or in early embryonic development. More complex chromosomal rearrangements can also occur as de novo events, which may help explain the variability in the condition's signs and symptoms. De novo chromosomal changes occur in people with no history of the disorder in their family. A small percentage of all people with Wolf-Hirschhorn syndrome have the disorder as a result of an unusual chromosomal abnormality such as a ring chromosome 4. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure. In the process, genes near the ends of the chromosome are lost. In the remaining cases of Wolf-Hirschhorn syndrome, an affected individual inherits a copy of chromosome 4 with a deleted segment. In these cases, one of the individual's parents carries a chromosomal rearrangement between chromosome 4 and another chromosome. This rearrangement is called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, translocations can become unbalanced as they are passed to the next generation. Some people with Wolf-Hirschhorn syndrome inherit an unbalanced translocation that deletes genes near the end of the short arm of chromosome 4. A loss of these genes results in the intellectual disability, slow growth, and other health problems characteristic of this disorder. | Wolf-Hirschhorn syndrome |
What are the treatments for Wolf-Hirschhorn syndrome ? | These resources address the diagnosis or management of Wolf-Hirschhorn syndrome: - Gene Review: Gene Review: Wolf-Hirschhorn Syndrome - Genetic Testing Registry: 4p partial monosomy syndrome - MedlinePlus Encyclopedia: Epilepsy 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 | Wolf-Hirschhorn syndrome |
What is (are) hereditary pancreatitis ? | Hereditary pancreatitis is a genetic condition characterized by recurrent episodes of inflammation of the pancreas (pancreatitis). The pancreas produces enzymes that help digest food, and it also produces insulin, a hormone that controls blood sugar levels in the body. Episodes of pancreatitis can lead to permanent tissue damage and loss of pancreatic function. Signs and symptoms of this condition usually begin in late childhood with an episode of acute pancreatitis. A sudden (acute) attack can cause abdominal pain, fever, nausea, or vomiting. An episode typically lasts from one to three days, although some people may experience severe episodes that last longer. Hereditary pancreatitis progresses to recurrent acute pancreatitis with multiple episodes of acute pancreatitis that recur over a period of at least a year; the number of episodes a person experiences varies. Recurrent acute pancreatitis leads to chronic pancreatitis, which occurs when the pancreas is persistently inflamed. Chronic pancreatitis usually develops by early adulthood in affected individuals. Signs and symptoms of chronic pancreatitis include occasional or frequent abdominal pain of varying severity, flatulence, and bloating. Many individuals with hereditary pancreatitis also develop abnormal calcium deposits in the pancreas (pancreatic calcifications) by early adulthood. Years of inflammation damage the pancreas, causing the formation of scar tissue (fibrosis) in place of functioning pancreatic tissue. Pancreatic fibrosis leads to the loss of pancreatic function in many affected individuals. This loss of function can impair the production of digestive enzymes and disrupt normal digestion, leading to fatty stool (steatorrhea), weight loss, and protein and vitamin deficiencies. Because of a decrease in insulin production due to a loss of pancreatic function, about a quarter of individuals with hereditary pancreatitis will develop type 1 diabetes mellitus by mid-adulthood; the risk of developing diabetes increases with age. Chronic pancreatic inflammation and damage to the pancreas increase the risk of developing pancreatic cancer. The risk is particularly high in people with hereditary pancreatitis who also smoke, use alcohol, have type 1 diabetes mellitus, or have a family history of cancer. In affected individuals who develop pancreatic cancer, it is typically diagnosed in mid-adulthood. Complications from pancreatic cancer and type 1 diabetes mellitus are the most common causes of death in individuals with hereditary pancreatitis, although individuals with this condition are thought to have a normal life expectancy. | hereditary pancreatitis |
How many people are affected by hereditary pancreatitis ? | Hereditary pancreatitis is thought to be a rare condition. In Europe, its prevalence is estimated to be 3 to 6 per million individuals. | hereditary pancreatitis |
What are the genetic changes related to hereditary pancreatitis ? | Mutations in the PRSS1 gene cause most cases of hereditary pancreatitis. The PRSS1 gene provides instructions for making an enzyme called cationic trypsinogen. This enzyme is produced in the pancreas and helps with the digestion of food. When cationic trypsinogen is needed, it is released (secreted) from the pancreas and transported to the small intestine, where it is cut (cleaved) into its working or active form called trypsin. When digestion is complete and trypsin is no longer needed, the enzyme is broken down. Some PRSS1 gene mutations that cause hereditary pancreatitis result in the production of a cationic trypsinogen enzyme that is prematurely converted to trypsin while it is still in the pancreas. Other mutations prevent trypsin from being broken down. These changes result in elevated levels of trypsin in the pancreas. Trypsin activity in the pancreas can damage pancreatic tissue and can also trigger an immune response, causing inflammation in the pancreas. It is estimated that 65 to 80 percent of people with hereditary pancreatitis have mutations in the PRSS1 gene. The remaining cases are caused by mutations in other genes, some of which have not been identified. | hereditary pancreatitis |
Is hereditary pancreatitis inherited ? | When hereditary pancreatitis is caused by mutations in the PRSS1 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 some cases, an affected person inherits the PRSS1 gene mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family. It is estimated that 20 percent of people who have the altered PRSS1 gene never have an episode of pancreatitis. (This situation is known as reduced penetrance.) It is unclear why some people with a mutated gene never develop signs and symptoms of the disease. | hereditary pancreatitis |
What are the treatments for hereditary pancreatitis ? | These resources address the diagnosis or management of hereditary pancreatitis: - Encyclopedia: Chronic Pancreatitis - Gene Review: Gene Review: PRSS1-Related Hereditary Pancreatitis - Gene Review: Gene Review: Pancreatitis Overview - Genetic Testing Registry: Hereditary pancreatitis - Johns Hopkins Medicine: Treatment Options for Pancreatitis - MD Anderson Cancer Center: Pancreatic Cancer Diagnosis - MedlinePlus Encyclopedia: Acute Pancreatitis - MedlinePlus Encyclopedia: Chronic Pancreatitis These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | hereditary pancreatitis |
What is (are) alternating hemiplegia of childhood ? | Alternating hemiplegia of childhood is a neurological condition characterized by recurrent episodes of temporary paralysis, often affecting one side of the body (hemiplegia). During some episodes, the paralysis alternates from one side of the body to the other or affects both sides at the same time. These episodes begin in infancy or early childhood, usually before 18 months of age, and the paralysis lasts from minutes to days. In addition to paralysis, affected individuals can have sudden attacks of uncontrollable muscle activity; these can cause involuntary limb movements (choreoathetosis), muscle tensing (dystonia), movement of the eyes (nystagmus), or shortness of breath (dyspnea). People with alternating hemiplegia of childhood may also experience sudden redness and warmth (flushing) or unusual paleness (pallor) of the skin. These attacks can occur during or separately from episodes of hemiplegia. The episodes of hemiplegia or uncontrolled movements can be triggered by certain factors, such as stress, extreme tiredness, cold temperatures, or bathing, although the trigger is not always known. A characteristic feature of alternating hemiplegia of childhood is that all symptoms disappear while the affected person is sleeping but can reappear shortly after awakening. The number and length of the episodes initially worsen throughout childhood but then begin to decrease over time. The uncontrollable muscle movements may disappear entirely, but the episodes of hemiplegia occur throughout life. Alternating hemiplegia of childhood also causes mild to severe cognitive problems. Almost all affected individuals have some level of developmental delay and intellectual disability. Their cognitive functioning typically declines over time. | alternating hemiplegia of childhood |
How many people are affected by alternating hemiplegia of childhood ? | Alternating hemiplegia of childhood is a rare condition that affects approximately 1 in 1 million people. | alternating hemiplegia of childhood |
What are the genetic changes related to alternating hemiplegia of childhood ? | Alternating hemiplegia of childhood is primarily caused by mutations in the ATP1A3 gene. Very rarely, a mutation in the ATP1A2 gene is involved in the condition. These genes provide instructions for making very similar proteins. They function as different forms of one piece, the alpha subunit, of a larger protein complex called Na+/K+ ATPase; the two versions of the complex are found in different parts of the brain. Both versions play a critical role in the normal function of nerve cells (neurons). Na+/K+ ATPase transports charged atoms (ions) into and out of neurons, which is an essential part of the signaling process that controls muscle movement. Mutations in the ATP1A3 or ATP1A2 gene reduce the activity of the Na+/K+ ATPase, impairing its ability to transport ions normally. It is unclear how a malfunctioning Na+/K+ ATPase causes the episodes of paralysis or uncontrollable movements characteristic of alternating hemiplegia of childhood. | alternating hemiplegia of childhood |
Is alternating hemiplegia of childhood inherited ? | Alternating hemiplegia of childhood is considered an autosomal dominant condition, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases of alternating hemiplegia of childhood result from new mutations in the gene and occur in people with no history of the disorder in their family. However, the condition can also run in families. For unknown reasons, the signs and symptoms are typically milder when the condition is found in multiple family members than when a single individual is affected. | alternating hemiplegia of childhood |
What are the treatments for alternating hemiplegia of childhood ? | These resources address the diagnosis or management of alternating hemiplegia of childhood: - The Great Ormond Street Hospital - University of Utah School of Medicine 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 | alternating hemiplegia of childhood |
What is (are) Partington syndrome ? | Partington syndrome is a neurological disorder that causes intellectual disability along with a condition called focal dystonia that particularly affects movement of the hands. Partington syndrome usually occurs in males; when it occurs in females, the signs and symptoms are often less severe. The intellectual disability associated with Partington syndrome usually ranges from mild to moderate. Some affected individuals have characteristics of autism spectrum disorders that affect communication and social interaction. Recurrent seizures (epilepsy) may also occur in Partington syndrome. Focal dystonia of the hands is a feature that distinguishes Partington syndrome from other intellectual disability syndromes. Dystonias are a group of movement problems characterized by involuntary, sustained muscle contractions; tremors; and other uncontrolled movements. The term "focal" refers to a type of dystonia that affects a single part of the body, in this case the hands. In Partington syndrome, focal dystonia of the hands, which is called the Partington sign, begins in early childhood and gradually gets worse. This condition typically causes difficulty with grasping movements or using a pen or pencil. People with Partington syndrome may also have dystonia affecting other parts of the body; dystonia affecting the muscles in the face and those involved in speech may cause impaired speech (dysarthria). People with this disorder may also have an awkward way of walking (gait). Signs and symptoms can vary widely, even within the same family. | Partington syndrome |
How many people are affected by Partington syndrome ? | The prevalence of Partington syndrome is unknown. About 20 cases have been described in the medical literature. | Partington syndrome |
What are the genetic changes related to Partington syndrome ? | Partington syndrome is caused by mutations in the ARX gene. This gene provides instructions for producing a protein that regulates the activity of other genes. Within the developing brain, the ARX protein is involved with movement (migration) and communication of nerve cells (neurons). In particular, this protein regulates genes that play a role in the migration of specialized neurons (interneurons) to their proper location. Interneurons relay signals between other neurons. The normal ARX protein contains four regions where a protein building block (amino acid) called alanine is repeated multiple times. These stretches of alanines are known as polyalanine tracts. The most common mutation that causes Partington syndrome, a duplication of genetic material written as c.428_451dup, adds extra alanines to the second polyalanine tract in the ARX protein. This type of mutation is called a polyalanine repeat expansion. The expansion likely impairs ARX protein function and may disrupt normal interneuron migration in the developing brain, leading to the intellectual disability and dystonia characteristic of Partington syndrome. | Partington syndrome |
Is Partington syndrome inherited ? | This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. Females with one altered copy of the gene may have some signs and symptoms related to the condition. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | Partington syndrome |
What are the treatments for Partington syndrome ? | These resources address the diagnosis or management of Partington syndrome: - American Academy of Child and Adolescent Psychiatry: Services in School for Children with Special Needs - American Academy of Pediatrics: What is a Developmental/Behavioral Pediatrician? - Centers for Disease Control and Prevention: Developmental Screening Fact Sheet - Genetic Testing Registry: Partington X-linked mental retardation 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 | Partington syndrome |
What is (are) Ewing sarcoma ? | Ewing sarcoma is a cancerous tumor that occurs in bones or soft tissues, such as cartilage or nerves. There are several types of Ewing sarcoma, including Ewing sarcoma of bone, extraosseous Ewing sarcoma, peripheral primitive neuroectodermal tumor (pPNET), and Askin tumor. These tumors are considered to be related because they have similar genetic causes. These types of Ewing sarcoma can be distinguished from one another by the tissue in which the tumor develops. Approximately 87 percent of Ewing sarcomas are Ewing sarcoma of bone, which is a bone tumor that usually occurs in the thigh bones (femurs), pelvis, ribs, or shoulder blades. Extraosseous (or extraskeletal) Ewing sarcoma describes tumors in the soft tissues around bones, such as cartilage. pPNETs occur in nerve tissue and can be found in many parts of the body. A type of pPNET found in the chest is called Askin tumor. Ewing sarcomas most often occur in children and young adults. Affected individuals usually feel stiffness, pain, swelling, or tenderness of the bone or surrounding tissue. Sometimes, there is a lump near the surface of the skin that feels warm and soft to the touch. Often, children have a fever that does not go away. Ewing sarcoma of bone can cause weakening of the involved bone, and affected individuals may have a broken bone with no obvious cause. It is common for Ewing sarcoma to spread to other parts of the body (metastasize), usually to the lungs, to other bones, or to the bone marrow. | Ewing sarcoma |
How many people are affected by Ewing sarcoma ? | Approximately 3 per 1 million children each year are diagnosed with a Ewing sarcoma. It is estimated that, in the United States, 250 children are diagnosed with one of these types of tumor each year. Ewing sarcoma accounts for about 1.5 percent of all childhood cancers, and it is the second most common type of bone tumor in children (the most common type of bone cancer is called osteosarcoma). | Ewing sarcoma |
What are the genetic changes related to Ewing sarcoma ? | The most common mutation that causes Ewing sarcoma involves two genes, the EWSR1 gene on chromosome 22 and the FLI1 gene on chromosome 11. A rearrangement (translocation) of genetic material between chromosomes 22 and 11, written as t(11;22), fuses part of the EWSR1 gene with part of the FLI1 gene, creating the EWSR1/FLI1 fusion gene. This mutation is acquired during a person's lifetime and is present only in tumor cells. This type of genetic change, called a somatic mutation, is not inherited. The protein produced from the EWSR1/FLI1 fusion gene, called EWS/FLI, has functions of the protein products of both genes. The FLI protein, produced from the FLI1 gene, attaches (binds) to DNA and regulates an activity called transcription, which is the first step in the production of proteins from genes. The FLI protein controls the growth and development of some cell types by regulating the transcription of certain genes. The EWS protein, produced from the EWSR1 gene, also regulates transcription. The EWS/FLI protein has the DNA-binding function of the FLI protein as well as the transcription regulation function of the EWS protein. It is thought that the EWS/FLI protein turns the transcription of a variety of genes on and off abnormally. This dysregulation of transcription leads to uncontrolled growth and division (proliferation) and abnormal maturation and survival of cells, causing tumor development. The EWSR1/FLI1 fusion gene occurs in approximately 85 percent of Ewing sarcomas. Translocations that fuse the EWSR1 gene with other genes that are related to the FLI1 gene can also cause these types of tumors, although these alternative translocations are relatively uncommon. The fusion proteins produced from the less common gene translocations have the same function as the EWS/FLI protein. | Ewing sarcoma |
Is Ewing sarcoma inherited ? | This condition is generally not inherited but arises from a mutation in the body's cells that occurs after conception. This alteration is called a somatic mutation. | Ewing sarcoma |
What are the treatments for Ewing sarcoma ? | These resources address the diagnosis or management of Ewing sarcoma: - Cancer.Net: Ewing Family of Tumors - Childhood: Diagnosis - Cancer.Net: Ewing Family of Tumors - Childhood: Treatment - Genetic Testing Registry: Ewing's sarcoma - MedlinePlus Encyclopedia: Ewing Sarcoma 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 | Ewing sarcoma |
What is (are) Tay-Sachs disease ? | Tay-Sachs disease is a rare inherited disorder that progressively destroys nerve cells (neurons) in the brain and spinal cord. The most common form of Tay-Sachs disease becomes apparent in infancy. Infants with this disorder typically appear normal until the age of 3 to 6 months, when their development slows and muscles used for movement weaken. Affected infants lose motor skills such as turning over, sitting, and crawling. They also develop an exaggerated startle reaction to loud noises. As the disease progresses, children with Tay-Sachs disease experience seizures, vision and hearing loss, intellectual disability, and paralysis. An eye abnormality called a cherry-red spot, which can be identified with an eye examination, is characteristic of this disorder. Children with this severe infantile form of Tay-Sachs disease usually live only into early childhood. Other forms of Tay-Sachs disease are very rare. Signs and symptoms can appear in childhood, adolescence, or adulthood and are usually milder than those seen with the infantile form. Characteristic features include muscle weakness, loss of muscle coordination (ataxia) and other problems with movement, speech problems, and mental illness. These signs and symptoms vary widely among people with late-onset forms of Tay-Sachs disease. | Tay-Sachs disease |
How many people are affected by Tay-Sachs disease ? | Tay-Sachs disease is very rare in the general population. The genetic mutations that cause this disease are more common in people of Ashkenazi (eastern and central European) Jewish heritage than in those with other backgrounds. The mutations responsible for this disease are also more common in certain French-Canadian communities of Quebec, the Old Order Amish community in Pennsylvania, and the Cajun population of Louisiana. | Tay-Sachs disease |
What are the genetic changes related to Tay-Sachs disease ? | Mutations in the HEXA gene cause Tay-Sachs disease. The HEXA gene provides instructions for making part of an enzyme called beta-hexosaminidase A, which plays a critical role in the brain and spinal cord. This enzyme is located in lysosomes, which are structures in cells that break down toxic substances and act as recycling centers. Within lysosomes, beta-hexosaminidase A helps break down a fatty substance called GM2 ganglioside. Mutations in the HEXA gene disrupt the activity of beta-hexosaminidase A, which prevents the enzyme from breaking down GM2 ganglioside. As a result, this substance accumulates to toxic levels, particularly in neurons in the brain and spinal cord. Progressive damage caused by the buildup of GM2 ganglioside leads to the destruction of these neurons, which causes the signs and symptoms of Tay-Sachs disease. Because Tay-Sachs disease impairs the function of a lysosomal enzyme and involves the buildup of GM2 ganglioside, this condition is sometimes referred to as a lysosomal storage disorder or a GM2-gangliosidosis. | Tay-Sachs disease |
Is Tay-Sachs 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. | Tay-Sachs disease |
What are the treatments for Tay-Sachs disease ? | These resources address the diagnosis or management of Tay-Sachs disease: - Gene Review: Gene Review: Hexosaminidase A Deficiency - Genetic Testing Registry: Tay-Sachs disease - MedlinePlus Encyclopedia: Tay-Sachs Disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | Tay-Sachs disease |
What is (are) glycogen storage disease type I ? | Glycogen storage disease type I (also known as GSDI or von Gierke disease) is an inherited disorder caused by the buildup of a complex sugar called glycogen in the body's cells. The accumulation of glycogen in certain organs and tissues, especially the liver, kidneys, and small intestines, impairs their ability to function normally. Signs and symptoms of this condition typically appear around the age of 3 or 4 months, when babies start to sleep through the night and do not eat as frequently as newborns. Affected infants may have low blood sugar (hypoglycemia), which can lead to seizures. They can also have a buildup of lactic acid in the body (lactic acidosis), high blood levels of a waste product called uric acid (hyperuricemia), and excess amounts of fats in the blood (hyperlipidemia). As they get older, children with GSDI have thin arms and legs and short stature. An enlarged liver may give the appearance of a protruding abdomen. The kidneys may also be enlarged. Affected individuals may also have diarrhea and deposits of cholesterol in the skin (xanthomas). People with GSDI may experience delayed puberty. Beginning in young to mid-adulthood, affected individuals may have thinning of the bones (osteoporosis), a form of arthritis resulting from uric acid crystals in the joints (gout), kidney disease, and high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension). Females with this condition may also have abnormal development of the ovaries (polycystic ovaries). In affected teens and adults, tumors called adenomas may form in the liver. Adenomas are usually noncancerous (benign), but occasionally these tumors can become cancerous (malignant). Researchers have described two types of GSDI, which differ in their signs and symptoms and genetic cause. These types are known as glycogen storage disease type Ia (GSDIa) and glycogen storage disease type Ib (GSDIb). Two other forms of GSDI have been described, and they were originally named types Ic and Id. However, these types are now known to be variations of GSDIb; for this reason, GSDIb is sometimes called GSD type I non-a. Many people with GSDIb have a shortage of white blood cells (neutropenia), which can make them prone to recurrent bacterial infections. Neutropenia is usually apparent by age 1. Many affected individuals also have inflammation of the intestinal walls (inflammatory bowel disease). People with GSDIb may have oral problems including cavities, inflammation of the gums (gingivitis), chronic gum (periodontal) disease, abnormal tooth development, and open sores (ulcers) in the mouth. The neutropenia and oral problems are specific to people with GSDIb and are typically not seen in people with GSDIa. | glycogen storage disease type I |
How many people are affected by glycogen storage disease type I ? | The overall incidence of GSDI is 1 in 100,000 individuals. GSDIa is more common than GSDIb, accounting for 80 percent of all GSDI cases. | glycogen storage disease type I |
What are the genetic changes related to glycogen storage disease type I ? | Mutations in two genes, G6PC and SLC37A4, cause GSDI. G6PC gene mutations cause GSDIa, and SLC37A4 gene mutations cause GSDIb. The proteins produced from the G6PC and SLC37A4 genes work together to break down a type of sugar molecule called glucose 6-phosphate. The breakdown of this molecule produces the simple sugar glucose, which is the primary energy source for most cells in the body. Mutations in the G6PC and SLC37A4 genes prevent the effective breakdown of glucose 6-phosphate. Glucose 6-phosphate that is not broken down to glucose is converted to glycogen and fat so it can be stored within cells. Too much glycogen and fat stored within a cell can be toxic. This buildup damages organs and tissues throughout the body, particularly the liver and kidneys, leading to the signs and symptoms of GSDI. | glycogen storage disease type I |
Is glycogen storage disease type I 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. | glycogen storage disease type I |
What are the treatments for glycogen storage disease type I ? | These resources address the diagnosis or management of glycogen storage disease type I: - American Liver Foundation - Canadian Liver Foundation - Gene Review: Gene Review: Glycogen Storage Disease Type I - Genetic Testing Registry: Glucose-6-phosphate transport defect - Genetic Testing Registry: Glycogen storage disease type 1A - Genetic Testing Registry: Glycogen storage disease, type I - MedlinePlus Encyclopedia: Von Gierke Disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care | glycogen storage disease type I |
What is (are) beta thalassemia ? | Beta thalassemia is a blood disorder that reduces the production of hemoglobin. Hemoglobin is the iron-containing protein in red blood cells that carries oxygen to cells throughout the body. In people with beta thalassemia, low levels of hemoglobin lead to a lack of oxygen in many parts of the body. Affected individuals also have a shortage of red blood cells (anemia), which can cause pale skin, weakness, fatigue, and more serious complications. People with beta thalassemia are at an increased risk of developing abnormal blood clots. Beta thalassemia is classified into two types depending on the severity of symptoms: thalassemia major (also known as Cooley's anemia) and thalassemia intermedia. Of the two types, thalassemia major is more severe. The signs and symptoms of thalassemia major appear within the first 2 years of life. Children develop life-threatening anemia. They do not gain weight and grow at the expected rate (failure to thrive) and may develop yellowing of the skin and whites of the eyes (jaundice). Affected individuals may have an enlarged spleen, liver, and heart, and their bones may be misshapen. Some adolescents with thalassemia major experience delayed puberty. Many people with thalassemia major have such severe symptoms that they need frequent blood transfusions to replenish their red blood cell supply. Over time, an influx of iron-containing hemoglobin from chronic blood transfusions can lead to a buildup of iron in the body, resulting in liver, heart, and hormone problems. Thalassemia intermedia is milder than thalassemia major. The signs and symptoms of thalassemia intermedia appear in early childhood or later in life. Affected individuals have mild to moderate anemia and may also have slow growth and bone abnormalities. | beta thalassemia |
How many people are affected by beta thalassemia ? | Beta thalassemia is a fairly common blood disorder worldwide. Thousands of infants with beta thalassemia are born each year. Beta thalassemia occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia. | beta thalassemia |
What are the genetic changes related to beta thalassemia ? | Mutations in the HBB gene cause beta thalassemia. The HBB gene provides instructions for making a protein called beta-globin. Beta-globin is a component (subunit) of hemoglobin. Hemoglobin consists of four protein subunits, typically two subunits of beta-globin and two subunits of another protein called alpha-globin. Some mutations in the HBB gene prevent the production of any beta-globin. The absence of beta-globin is referred to as beta-zero (B0) thalassemia. Other HBB gene mutations allow some beta-globin to be produced but in reduced amounts. A reduced amount of beta-globin is called beta-plus (B+) thalassemia. Having either B0 or B+ thalassemia does not necessarily predict disease severity, however; people with both types have been diagnosed with thalassemia major and thalassemia intermedia. A lack of beta-globin leads to a reduced amount of functional hemoglobin. Without sufficient hemoglobin, red blood cells do not develop normally, causing a shortage of mature red blood cells. The low number of mature red blood cells leads to anemia and other associated health problems in people with beta thalassemia. | beta thalassemia |
Is beta thalassemia inherited ? | Thalassemia major and thalassemia intermedia are inherited in an autosomal recessive pattern, which means both copies of the HBB 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. Sometimes, however, people with only one HBB gene mutation in each cell develop mild anemia. These mildly affected people are said to have thalassemia minor. In a small percentage of families, the HBB gene mutation is inherited in an autosomal dominant manner. In these cases, one copy of the altered gene in each cell is sufficient to cause the signs and symptoms of beta thalassemia. | beta thalassemia |
What are the treatments for beta thalassemia ? | These resources address the diagnosis or management of beta thalassemia: - Gene Review: Gene Review: Beta-Thalassemia - Genetic Testing Registry: Beta-thalassemia, dominant inclusion body type - Genetic Testing Registry: beta Thalassemia - MedlinePlus Encyclopedia: Thalassemia 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 | beta thalassemia |
What is (are) Leigh syndrome ? | Leigh syndrome is a severe neurological disorder that typically arises in the first year of life. This condition is characterized by progressive loss of mental and movement abilities (psychomotor regression) and typically results in death within a couple of years, usually due to respiratory failure. A small number of individuals develop symptoms in adulthood or have symptoms that worsen more slowly. The first signs of Leigh syndrome seen in infancy are usually vomiting, diarrhea, and difficulty swallowing (dysphagia) that leads to eating problems. These problems often result in an inability to grow and gain weight at the expected rate (failure to thrive). Severe muscle and movement problems are common in Leigh syndrome. Affected individuals may develop weak muscle tone (hypotonia), involuntary muscle contractions (dystonia), and problems with movement and balance (ataxia). Loss of sensation and weakness in the limbs (peripheral neuropathy), common in people with Leigh syndrome, may also make movement difficult. Several other features may occur in people with Leigh syndrome. Many affected individuals develop weakness or paralysis of the muscles that move the eyes (ophthalmoparesis); rapid, involuntary eye movements (nystagmus); or degeneration of the nerves that carry information from the eyes to the brain (optic atrophy). Severe breathing problems are common in people with Leigh syndrome, and these problems can worsen until they cause acute respiratory failure. Some affected individuals develop hypertrophic cardiomyopathy, which is a thickening of the heart muscle that forces the heart to work harder to pump blood. In addition, a substance called lactate can build up in the body, and excessive amounts are often found in the blood, cerebrospinal fluid, or urine of people with Leigh syndrome. The signs and symptoms of Leigh syndrome are caused in part by patches of damaged tissue (lesions) that develop in the brains of people with this condition. A procedure called magnetic resonance imaging (MRI) reveals characteristic lesions in certain regions of the brain and the brainstem (the part of the brain that is connected to the spinal cord). These regions include the basal ganglia, which help control movement; the cerebellum, which controls the ability to balance and coordinates movement; and the brainstem, which controls functions such as swallowing, breathing, hearing, and seeing. The brain lesions are often accompanied by loss of the myelin coating around nerves (demyelination), which reduces the ability of the nerves to activate muscles used for movement or relay sensory information back to the brain. | Leigh syndrome |
How many people are affected by Leigh syndrome ? | Leigh syndrome affects at least 1 in 40,000 newborns. The condition is more common in certain populations. For example, the condition occurs in approximately 1 in 2,000 newborns in the Saguenay Lac-Saint-Jean region of Quebec, Canada. | Leigh syndrome |
What are the genetic changes related to Leigh syndrome ? | Leigh syndrome can be caused by mutations in one of over 30 different genes. In humans, most genes are found in DNA in the cell's nucleus, called nuclear DNA. However, some genes are found in DNA in specialized structures in the cell called mitochondria. This type of DNA is known as mitochondrial DNA (mtDNA). While most people with Leigh syndrome have a mutation in nuclear DNA, about 20 to 25 percent have a mutation in mtDNA. Most genes associated with Leigh syndrome are involved in the process of energy production in mitochondria. Mitochondria use oxygen to convert the energy from food into a form cells can use. Five protein complexes, made up of several proteins each, are involved in this process, called oxidative phosphorylation. The complexes are named complex I, complex II, complex III, complex IV, and complex V. During oxidative phosphorylation, the protein complexes drive the production of ATP, the cell's main energy source, through a step-by-step transfer of negatively charged particles called electrons. Many of the gene mutations associated with Leigh syndrome affect proteins in complexes I, II, IV, or V or disrupt the assembly of these complexes. These mutations reduce or eliminate the activity of one or more of these complexes, which can lead to Leigh syndrome. Disruption of complex IV, also called cytochrome c oxidase or COX, is the most common cause of Leigh syndrome. The most frequently mutated gene in COX-deficient Leigh syndrome is called SURF1. This gene, which is found in nuclear DNA, provides instructions for making a protein that helps assemble the COX protein complex (complex IV). The COX protein complex, which is involved in the last step of electron transfer in oxidative phosphorylation, provides the energy that will be used in the next step of the process to generate ATP. Mutations in the SURF1 gene typically lead to an abnormally short SURF1 protein that is broken down in cells, resulting in the absence of functional SURF1 protein. The loss of this protein reduces the formation of normal COX complexes, which impairs mitochondrial energy production. Other nuclear DNA mutations associated with Leigh syndrome decrease the activity of other oxidative phosphorylation protein complexes or affect additional steps related to energy production. For example, Leigh syndrome can be caused by mutations in genes that form the pyruvate dehydrogenase complex. These mutations lead to a shortage of pyruvate dehydrogenase, an enzyme involved in mitochondrial energy production. The most common mtDNA mutation in Leigh syndrome affects the MT-ATP6 gene, which provides instructions for making a piece of complex V, also known as the ATP synthase protein complex. Using the energy provided by the other protein complexes, the ATP synthase complex generates ATP. MT-ATP6 gene mutations, found in 10 to 20 percent of people with Leigh syndrome, block the generation of ATP. Other mtDNA mutations associated with Leigh syndrome decrease the activity of other oxidative phosphorylation protein complexes or lead to reduced mitochondrial protein synthesis, all of which impair mitochondrial energy production. Although the exact mechanism is unclear, researchers believe that impaired oxidative phosphorylation can lead to cell death because of decreased energy available in the cell. Certain tissues that require large amounts of energy, such as the brain, muscles, and heart, seem especially sensitive to decreases in cellular energy. Cell death in the brain likely causes the characteristic lesions seen in Leigh syndrome, which contribute to the signs and symptoms of the condition. Cell death in other sensitive tissues may also contribute to the features of Leigh syndrome. | Leigh syndrome |
Is Leigh syndrome inherited ? | Leigh syndrome can have different inheritance patterns. It is most commonly inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. This pattern of inheritance applies to genes contained in nuclear DNA. 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. In about 20 to 25 percent of people with Leigh syndrome, the condition is inherited in a mitochondrial pattern, which is also known as maternal inheritance. This pattern of inheritance applies to genes contained in mtDNA. Because egg cells, but not sperm cells, contribute mitochondria to the developing embryo, children can only inherit disorders resulting from mtDNA mutations from their mother. These disorders can appear in every generation of a family and can affect both males and females, but fathers do not pass traits associated with changes in mtDNA to their children. Occasionally, mutations in mtDNA occur spontaneously, and there is no history of Leigh syndrome in the family. In a small number of affected individuals with mutations in nuclear DNA, Leigh syndrome is inherited in an X-linked recessive pattern. The condition has this pattern of inheritance when the mutated gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. | Leigh syndrome |
What are the treatments for Leigh syndrome ? | These resources address the diagnosis or management of Leigh syndrome: - Gene Review: Gene Review: Mitochondrial DNA-Associated Leigh Syndrome and NARP - Gene Review: Gene Review: Nuclear Gene-Encoded Leigh Syndrome Overview - Genetic Testing Registry: Leigh Syndrome (mtDNA mutation) - Genetic Testing Registry: Leigh Syndrome (nuclear DNA mutation) - Genetic Testing Registry: Leigh syndrome - Genetic Testing Registry: Leigh syndrome, French Canadian type 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 | Leigh syndrome |
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