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genetic changes | What are the genetic changes related to congenital mirror movement disorder ? | Congenital mirror movement disorder can be caused by mutations in the DCC or RAD51 gene; mutations in these genes account for a total of about 35 percent of cases. Mutations in other genes that have not been identified likely account for other cases of this disorder. The DCC gene provides instructions for making a protein called the netrin-1 receptor, which is involved in the development of the nervous system. This receptor attaches (binds) to a substance called netrin-1, fitting together like a lock and its key. The binding of netrin-1 to its receptor triggers signaling that helps direct the growth of specialized nerve cell extensions called axons, which transmit nerve impulses that signal muscle movement. Normally, signals from each half of the brain control movements on the opposite side of the body. Binding of netrin-1 to its receptor inhibits axons from developing in ways that would carry movement signals from each half of the brain to the same side of the body. Mutations in the DCC gene result in an impaired or missing netrin-1 receptor protein. A shortage of functional netrin-1 receptor protein impairs control of axon growth during nervous system development. As a result, movement signals from each half of the brain are abnormally transmitted to both sides of the body, leading to mirror movements. The RAD51 gene provides instructions for making a protein that is also thought to be involved in the development of nervous system functions that control movement, but its role in this development is unclear. Mutations in the RAD51 gene result in a missing or impaired RAD51 protein, but it is unknown how a shortage of functional RAD51 protein affects nervous system development and leads to the signs and symptoms of congenital mirror movement disorder. |
inheritance | Is congenital mirror movement disorder inherited ? | In most cases, including those caused by mutations in the DCC or RAD51 gene, this condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the altered gene. Some people who have the altered gene never develop the condition, a situation known as reduced penetrance. Research suggests that in rare cases, this condition may be 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. |
treatment | What are the treatments for congenital mirror movement disorder ? | These resources address the diagnosis or management of congenital mirror movement disorder: - Gene Review: Gene Review: Congenital Mirror Movements - Genetic Testing Registry: Mirror movements 2 - Genetic Testing Registry: Mirror movements, congenital - KidsHealth: Occupational Therapy 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 |
information | What is (are) Duane-radial ray syndrome ? | Duane-radial ray syndrome is a disorder that affects the eyes and causes abnormalities of bones in the arms and hands. This condition is characterized by a particular problem with eye movement called Duane anomaly (also known as Duane syndrome). This abnormality results from the improper development of certain nerves that control eye movement. Duane anomaly limits outward eye movement (toward the ear), and in some cases may limit inward eye movement (toward the nose). Also, as the eye moves inward, the eye opening becomes narrower and the eyeball may pull back (retract) into its socket. Bone abnormalities in the hands include malformed or absent thumbs, an extra thumb, or a long thumb that looks like a finger. Partial or complete absence of bones in the forearm is also common. Together, these hand and arm abnormalities are known as radial ray malformations. People with the combination of Duane anomaly and radial ray malformations may have a variety of other signs and symptoms. These features include unusually shaped ears, hearing loss, heart and kidney defects, a distinctive facial appearance, an inward- and upward-turning foot (clubfoot), and fused spinal bones (vertebrae). The varied signs and symptoms of Duane-radial ray syndrome often overlap with features of other disorders. For example, acro-renal-ocular syndrome is characterized by Duane anomaly and other eye abnormalities, radial ray malformations, and kidney defects. Both conditions are caused by mutations in the same gene. Based on these similarities, researchers suspect that Duane-radial ray syndrome and acro-renal-ocular syndrome are part of an overlapping set of syndromes with many possible signs and symptoms. The features of Duane-radial ray syndrome are also similar to those of a condition called Holt-Oram syndrome; however, these two disorders are caused by mutations in different genes. |
frequency | How many people are affected by Duane-radial ray syndrome ? | Duane-radial ray syndrome is a rare condition whose prevalence is unknown. Only a few affected families have been reported worldwide. |
genetic changes | What are the genetic changes related to Duane-radial ray syndrome ? | Duane-radial ray syndrome results from mutations in the SALL4 gene. This gene is part of a group of genes called the SALL family. SALL genes provide instructions for making proteins that are involved in the formation of tissues and organs before birth. The proteins produced from these genes act as transcription factors, which means they attach (bind) to specific regions of DNA and help control the activity of particular genes. The exact function of the SALL4 protein is unclear, although it appears to be important for the normal development of the eyes, heart, and limbs. Mutations in the SALL4 gene prevent cells from making any functional protein from one copy of the gene. It is unclear how a reduction in the amount of the SALL4 protein leads to Duane anomaly, radial ray malformations, and the other features of Duane-radial ray syndrome and similar conditions. |
inheritance | Is Duane-radial ray syndrome inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered SALL4 gene in each cell is sufficient to cause the disorder. In many cases, an affected person inherits a 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. |
treatment | What are the treatments for Duane-radial ray syndrome ? | These resources address the diagnosis or management of Duane-radial ray syndrome: - Gene Review: Gene Review: SALL4-Related Disorders - Genetic Testing Registry: Duane-radial ray syndrome - MedlinePlus Encyclopedia: Skeletal Limb Abnormalities 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 |
information | What is (are) prion disease ? | Prion disease represents a group of conditions that affect the nervous system in humans and animals. In people, these conditions impair brain function, causing changes in memory, personality, and behavior; a decline in intellectual function (dementia); and abnormal movements, particularly difficulty with coordinating movements (ataxia). The signs and symptoms of prion disease typically begin in adulthood and worsen with time, leading to death within a few months to several years. |
frequency | How many people are affected by prion disease ? | These disorders are very rare. Although the exact prevalence of prion disease is unknown, studies suggest that this group of conditions affects about one person per million worldwide each year. Approximately 350 new cases are reported annually in the United States. |
genetic changes | What are the genetic changes related to prion disease ? | Between 10 and 15 percent of all cases of prion disease are caused by mutations in the PRNP gene. Because they can run in families, these forms of prion disease are classified as familial. Familial prion diseases, which have overlapping signs and symptoms, include familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Strussler-Scheinker syndrome (GSS), and fatal familial insomnia (FFI). The PRNP gene provides instructions for making a protein called prion protein (PrP). Although the precise function of this protein is unknown, researchers have proposed roles in several important processes. These include the transport of copper into cells, protection of brain cells (neurons) from injury (neuroprotection), and communication between neurons. In familial forms of prion disease, PRNP gene mutations result in the production of an abnormally shaped protein, known as PrPSc, from one copy of the gene. In a process that is not fully understood, PrPSc can attach (bind) to the normal protein (PrPC) and promote its transformation into PrPSc. The abnormal protein builds up in the brain, forming clumps that damage or destroy neurons. The loss of these cells creates microscopic sponge-like holes (vacuoles) in the brain, which leads to the signs and symptoms of prion disease. The other 85 to 90 percent of cases of prion disease are classified as either sporadic or acquired. People with sporadic prion disease have no family history of the disease and no identified mutation in the PRNP gene. Sporadic disease occurs when PrPC spontaneously, and for unknown reasons, is transformed into PrPSc. Sporadic forms of prion disease include sporadic Creutzfeldt-Jakob disease (sCJD), sporadic fatal insomnia (sFI), and variably protease-sensitive prionopathy (VPSPr). Acquired prion disease results from exposure to PrPSc from an outside source. For example, variant Creutzfeldt-Jakob disease (vCJD) is a type of acquired prion disease in humans that results from eating beef products containing PrPSc from cattle with prion disease. In cows, this form of the disease is known as bovine spongiform encephalopathy (BSE) or, more commonly, "mad cow disease." Another example of an acquired human prion disease is kuru, which was identified in the South Fore population in Papua New Guinea. The disorder was transmitted when individuals ate affected human tissue during cannibalistic funeral rituals. Rarely, prion disease can be transmitted by accidental exposure to PrPSc-contaminated tissues during a medical procedure. This type of prion disease, which accounts for 1 to 2 percent of all cases, is classified as iatrogenic. |
inheritance | Is prion disease inherited ? | Familial forms of prion disease are inherited in an autosomal dominant pattern, which means one copy of the altered PRNP gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the altered gene from one affected parent. In some people, familial forms of prion disease are caused by a new mutation in the gene that occurs during the formation of a parent's reproductive cells (eggs or sperm) or in early embryonic development. Although such people do not have an affected parent, they can pass the genetic change to their children. The sporadic, acquired, and iatrogenic forms of prion disease, including kuru and variant Creutzfeldt-Jakob disease, are not inherited. |
treatment | What are the treatments for prion disease ? | These resources address the diagnosis or management of prion disease: - Creutzfeldt-Jakob Disease Foundation: Suggestions for Patient Care - Gene Review: Gene Review: Genetic Prion Diseases - Genetic Testing Registry: Genetic prion diseases - MedlinePlus Encyclopedia: Creutzfeldt-Jakob disease - MedlinePlus Encyclopedia: Kuru - University of California, San Fransisco Memory and Aging Center: Living With Creutzfeldt-Jakob Disease - University of California, San Fransisco Memory and Aging Center: Treatments for Creutzfeldt-Jakob 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 |
information | What is (are) X-linked myotubular myopathy ? | X-linked myotubular myopathy is a condition that primarily affects muscles used for movement (skeletal muscles) and occurs almost exclusively in males. People with this condition have muscle weakness (myopathy) and decreased muscle tone (hypotonia) that are usually evident at birth. The muscle problems in X-linked myotubular myopathy impair the development of motor skills such as sitting, standing, and walking. Affected infants may also have difficulties with feeding due to muscle weakness. Individuals with this condition often do not have the muscle strength to breathe on their own and must be supported with a machine to help them breathe (mechanical ventilation). Some affected individuals need breathing assistance only periodically, typically during sleep, while others require it continuously. People with X-linked myotubular myopathy may also have weakness in the muscles that control eye movement (ophthalmoplegia), weakness in other muscles of the face, and absent reflexes (areflexia). In X-linked myotubular myopathy, muscle weakness often disrupts normal bone development and can lead to fragile bones, an abnormal curvature of the spine (scoliosis), and joint deformities (contractures) of the hips and knees. People with X-linked myotubular myopathy may have a large head with a narrow and elongated face and a high, arched roof of the mouth (palate). They may also have liver disease, recurrent ear and respiratory infections, or seizures. Because of their severe breathing problems, individuals with X-linked myotubular myopathy usually survive only into early childhood; however, some people with this condition have lived into adulthood. X-linked myotubular myopathy is a member of a group of disorders called centronuclear myopathies. In centronuclear myopathies, the nucleus is found at the center of many rod-shaped muscle cells instead of at either end, where it is normally located. |
frequency | How many people are affected by X-linked myotubular myopathy ? | The incidence of X-linked myotubular myopathy is estimated to be 1 in 50,000 newborn males worldwide. |
genetic changes | What are the genetic changes related to X-linked myotubular myopathy ? | Mutations in the MTM1 gene cause X-linked myotubular myopathy. The MTM1 gene provides instructions for producing an enzyme called myotubularin. Myotubularin is thought to be involved in the development and maintenance of muscle cells. MTM1 gene mutations probably disrupt myotubularin's role in muscle cell development and maintenance, causing muscle weakness and other signs and symptoms of X-linked myotubular myopathy. |
inheritance | Is X-linked myotubular myopathy inherited ? | X-linked myotubular myopathy 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 must be present 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. In X-linked myotubular myopathy, the affected male inherits one altered copy from his mother in 80 to 90 percent of cases. In the remaining 10 to 20 percent of cases, the disorder results from a new mutation in the gene that occurs during the formation of a parent's reproductive cells (eggs or sperm) or in early embryonic development. Females with one altered copy of the MTM1 gene generally do not experience signs and symptoms of the disorder. In rare cases, however, females who have one altered copy of the MTM1 gene experience some mild muscle weakness. |
treatment | What are the treatments for X-linked myotubular myopathy ? | These resources address the diagnosis or management of X-linked myotubular myopathy: - Gene Review: Gene Review: X-Linked Centronuclear Myopathy - Genetic Testing Registry: Severe X-linked myotubular 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 |
information | What is (are) hyperphosphatemic familial tumoral calcinosis ? | Hyperphosphatemic familial tumoral calcinosis (HFTC) is a condition characterized by an increase in the levels of phosphate in the blood (hyperphosphatemia) and abnormal deposits of phosphate and calcium (calcinosis) in the body's tissues. Calcinosis typically develops in early childhood to early adulthood, although in some people the deposits first appear in infancy or in late adulthood. Calcinosis usually occurs in and just under skin tissue around the joints, most often the hips, shoulders, and elbows. Calcinosis may also develop in the soft tissue of the feet, legs, and hands. Rarely, calcinosis occurs in blood vessels or in the brain and can cause serious health problems. The deposits develop over time and vary in size. Larger deposits form masses that are noticeable under the skin and can interfere with the function of joints and impair movement. These large deposits may appear tumor-like (tumoral), but they are not tumors or cancerous. The number and frequency of deposits varies among affected individuals; some develop few deposits during their lifetime, while others may develop many in a short period of time. Other features of HFTC include eye abnormalities such as calcium buildup in the clear front covering of the eye (corneal calcification) or angioid streaks that occur when tiny breaks form in the layer of tissue at the back of the eye called Bruch's membrane. Inflammation of the long bones (diaphysis) or excessive bone growth (hyperostosis) may occur. Some affected individuals have dental abnormalities. In males, small crystals of cholesterol can accumulate (microlithiasis) in the testicles, which usually causes no health problems. A similar condition called hyperphosphatemia-hyperostosis syndrome (HHS) results in increased levels of phosphate in the blood, excessive bone growth, and bone lesions. This condition used to be considered a separate disorder, but it is now thought to be a mild variant of HFTC. |
frequency | How many people are affected by hyperphosphatemic familial tumoral calcinosis ? | The prevalence of HFTC is unknown, but it is thought to be a rare condition. It occurs most often in Middle Eastern and African populations. |
genetic changes | What are the genetic changes related to hyperphosphatemic familial tumoral calcinosis ? | Mutations in the FGF23, GALNT3, or KL gene cause HFTC. The proteins produced from these genes are all involved in the regulation of phosphate levels within the body (phosphate homeostasis). Among its many functions, phosphate plays a critical role in the formation and growth of bones in childhood and helps maintain bone strength in adults. Phosphate levels are controlled in large part by the kidneys. The kidneys normally rid the body of excess phosphate by excreting it in urine, and they reabsorb this mineral into the bloodstream when more is needed. The FGF23 gene provides instructions for making a protein called fibroblast growth factor 23, which is produced in bone cells and signals the kidneys to stop reabsorbing phosphate. The proteins produced from the GALNT3 and KL genes help to regulate fibroblast growth factor 23. The protein produced from the GALNT3 gene, called ppGalNacT3, attaches sugar molecules to fibroblast growth factor 23 in a process called glycosylation. Glycosylation allows fibroblast growth factor 23 to move out of the cell and protects the protein from being broken down. Once outside the bone cell, fibroblast growth factor 23 must attach (bind) to a receptor protein that spans the membrane of kidney cells. The protein produced from the KL gene, called alpha-klotho, turns on (activates) the receptor protein so that fibroblast growth factor 23 can bind to it. Binding of fibroblast growth factor 23 to its receptor stimulates signaling that stops phosphate reabsorption into the bloodstream. Mutations in the FGF23, GALNT3, or KL gene lead to a disruption in fibroblast growth factor 23 signaling. FGF23 gene mutations result in the production of a protein with decreased function that quickly gets broken down. Mutations in the GALNT3 gene result in the production of ppGalNacT3 protein with little or no function. As a result, the protein cannot glycosylate fibroblast growth factor 23, which is consequently trapped inside the cell and broken down rather than being released from the cell (secreted). KL gene mutations lead to a shortage of functional alpha-klotho. As a result, the receptor protein is not activated, causing it to be unavailable to be bound to fibroblast growth factor 23. All of these impairments to fibroblast growth factor 23 function and signaling lead to increased phosphate absorption by the kidneys. Calcinosis results when the excess phosphate combines with calcium to form deposits that build up in soft tissues. Although phosphate levels are increased, calcium is typically within the normal range. |
inheritance | Is hyperphosphatemic familial tumoral calcinosis 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. |
treatment | What are the treatments for hyperphosphatemic familial tumoral calcinosis ? | These resources address the diagnosis or management of hyperphosphatemic familial tumoral calcinosis: - Genetic Testing Registry: Tumoral calcinosis, familial, hyperphosphatemic 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 |
information | What is (are) frontometaphyseal dysplasia ? | Frontometaphyseal dysplasia is a disorder involving abnormalities in skeletal development and other health problems. It is a member of a group of related conditions called otopalatodigital spectrum disorders, which also includes otopalatodigital syndrome type 1, otopalatodigital syndrome type 2, and Melnick-Needles syndrome. In general, these disorders involve hearing loss caused by malformations in the tiny bones in the ears (ossicles), problems in the development of the roof of the mouth (palate), and skeletal abnormalities involving the fingers and/or toes (digits). Frontometaphyseal dysplasia is distinguished from the other otopalatodigital spectrum disorders by the presence of joint deformities called contractures that restrict the movement of certain joints. People with frontometaphyseal dysplasia may also have bowed limbs, an abnormal curvature of the spine (scoliosis), and abnormalities of the fingers and hands. Characteristic facial features may include prominent brow ridges; wide-set and downward-slanting eyes; a very small lower jaw and chin (micrognathia); and small, missing or misaligned teeth. Some affected individuals have hearing loss. In addition to skeletal abnormalities, individuals with frontometaphyseal dysplasia may have obstruction of the ducts between the kidneys and bladder (ureters), heart defects, or constrictions in the passages leading from the windpipe to the lungs (the bronchi) that can cause problems with breathing. Males with frontometaphyseal dysplasia generally have more severe signs and symptoms of the disorder than do females, who may show only the characteristic facial features. |
frequency | How many people are affected by frontometaphyseal dysplasia ? | Frontometaphyseal dysplasia is a rare disorder; only a few dozen cases have been reported worldwide. |
genetic changes | What are the genetic changes related to frontometaphyseal dysplasia ? | Mutations in the FLNA gene cause frontometaphyseal dysplasia. The FLNA gene provides instructions for producing the protein filamin A, which helps build the network of protein filaments (cytoskeleton) that gives structure to cells and allows them to change shape and move. Filamin A binds to another protein called actin, and helps the actin to form the branching network of filaments that make up the cytoskeleton. Filamin A also links actin to many other proteins to perform various functions within the cell. A small number of mutations in the FLNA gene have been identified in people with frontometaphyseal dysplasia. These mutations are described as "gain-of-function" because they appear to enhance the activity of the filamin A protein or give the protein a new, atypical function. Researchers believe that the mutations may change the way the filamin A protein helps regulate processes involved in skeletal development, but it is not known how changes in the protein relate to the specific signs and symptoms of frontometaphyseal dysplasia. |
inheritance | Is frontometaphyseal dysplasia inherited ? | This condition is inherited in an X-linked dominant pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In females (who have two X chromosomes), a mutation in one of the two copies of the gene in each cell is sufficient to cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of the gene in each cell causes the disorder. In most cases, males experience more severe symptoms of the disorder than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for frontometaphyseal dysplasia ? | These resources address the diagnosis or management of frontometaphyseal dysplasia: - Gene Review: Gene Review: Otopalatodigital Spectrum Disorders - Genetic Testing Registry: Frontometaphyseal dysplasia 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 |
information | What is (are) Mabry syndrome ? | Mabry syndrome is a condition characterized by intellectual disability, distinctive facial features, increased levels of an enzyme called alkaline phosphatase in the blood (hyperphosphatasia), and other signs and symptoms. People with Mabry syndrome have intellectual disability that is often moderate to severe. They typically have little to no speech development and are delayed in the development of motor skills (such as sitting, crawling, and walking). Many affected individuals have low muscle tone (hypotonia) and develop recurrent seizures (epilepsy) in early childhood. Seizures are usually the generalized tonic-clonic type, which involve muscle rigidity, convulsions, and loss of consciousness. Individuals with Mabry syndrome have distinctive facial features that include wide-set eyes (hypertelorism), long openings of the eyelids (long palpebral fissures), a nose with a broad bridge and a rounded tip, downturned corners of the mouth, and a thin upper lip. These facial features usually become less pronounced over time. Hyperphosphatasia begins within the first year of life in people with Mabry syndrome. There are many different types of alkaline phosphatase found in tissues; the type that is increased in Mabry syndrome is called the tissue non-specific type and is found throughout the body. In affected individuals, alkaline phosphatase levels in the blood are usually increased by one to two times the normal amount, but can be up to 20 times higher than normal. The elevated enzyme levels remain relatively stable over a person's lifetime. Hyperphosphatasia appears to cause no negative health effects, but this finding can help health professionals diagnose Mabry syndrome. Another common feature of Mabry syndrome is shortened bones at the ends of fingers (brachytelephalangy), which can be seen on x-ray imaging. Underdeveloped fingernails (nail hypoplasia) may also occur. Sometimes, individuals with Mabry syndrome have abnormalities of the digestive system, including narrowing or blockage of the anus (anal stenosis or anal atresia) or Hirschsprung disease, a disorder that causes severe constipation or blockage of the intestine. Rarely, affected individuals experience hearing loss. The signs and symptoms of Mabry syndrome vary among affected individuals. Those who are least severely affected have only intellectual disability and hyperphosphatasia, without distinctive facial features or the other health problems listed above. |
frequency | How many people are affected by Mabry syndrome ? | Mabry syndrome is likely a rare condition, but its prevalence is unknown. More than 20 cases have been described in the scientific literature. |
genetic changes | What are the genetic changes related to Mabry syndrome ? | Mutations in the PIGV, PIGO, or PGAP2 gene cause Mabry syndrome. These genes are all involved in the production (synthesis) of a molecule called a glycosylphosphosphatidylinositol (GPI) anchor. This molecule is synthesized in a series of steps. It then attaches (binds) to various proteins and binds them to the outer surface of the cell membrane, ensuring that they are available when needed. Alkaline phosphatase is an example of a protein that is bound to the cell membrane by a GPI anchor. The proteins produced from the PIGV and PIGO genes are involved in piecing together the GPI anchor. After the complete GPI anchor is attached to a protein, the protein produced from the PGAP2 gene adjusts the anchor to enhance the anchor's ability to bind to the cell membrane. Mutations in the PIGV, PIGO, or PGAP2 gene result in the production of an incomplete GPI anchor that cannot attach to proteins or to cell membranes. Proteins lacking a functional GPI anchor cannot bind to the cell membrane and are instead released from the cell. The release of non-GPI anchored alkaline phosphatase elevates the amount of this protein in the blood, causing hyperphosphatasia in people with Mabry syndrome. It is unclear how gene mutations lead to the other features of Mabry syndrome, but these signs and symptoms are likely due to a lack of proper GPI anchoring of proteins. PIGV gene mutations are the most frequent cause of Mabry syndrome, accounting for approximately half of all cases. Mutations in the PIGO and PGAP2 genes are responsible for a small proportion of Mabry syndrome. The remaining affected individuals do not have an identified mutation in any of these three genes; the cause of the condition in these individuals is unknown. |
inheritance | Is Mabry 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. |
treatment | What are the treatments for Mabry syndrome ? | These resources address the diagnosis or management of Mabry syndrome: - Genetic Testing Registry: Hyperphosphatasia with mental retardation syndrome - Genetic Testing Registry: Hyperphosphatasia with mental retardation syndrome 1 - Genetic Testing Registry: Hyperphosphatasia with mental retardation syndrome 2 - Genetic Testing Registry: Hyperphosphatasia with mental retardation syndrome 3 - MedlinePlus Encyclopedia: ALP Isoenzyme Test - MedlinePlus Encyclopedia: ALP--Blood Test - Seattle Children's Hospital: Hirschsprung's Disease--Treatments These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) harlequin ichthyosis ? | Harlequin ichthyosis is a severe genetic disorder that mainly affects the skin. Infants with this condition are born with very hard, thick skin covering most of their bodies. The skin forms large, diamond-shaped plates that are separated by deep cracks (fissures). These skin abnormalities affect the shape of the eyelids, nose, mouth, and ears, and limit movement of the arms and legs. Restricted movement of the chest can lead to breathing difficulties and respiratory failure. The skin normally forms a protective barrier between the body and its surrounding environment. The skin abnormalities associated with harlequin ichthyosis disrupt this barrier, making it more difficult for affected infants to control water loss, regulate their body temperature, and fight infections. Infants with harlequin ichthyosis often experience an excessive loss of fluids (dehydration) and develop life-threatening infections in the first few weeks of life. It used to be very rare for affected infants to survive the newborn period. However, with intensive medical support and improved treatment, people with this disorder now have a better chance of living into childhood and adolescence. |
frequency | How many people are affected by harlequin ichthyosis ? | Harlequin ichthyosis is very rare; its exact incidence is unknown. |
genetic changes | What are the genetic changes related to harlequin ichthyosis ? | Mutations in the ABCA12 gene cause harlequin ichthyosis. The ABCA12 gene provides instructions for making a protein that is essential for the normal development of skin cells. This protein plays a major role in the transport of fats (lipids) in the outermost layer of skin (the epidermis). Some mutations in the ABCA12 gene prevent the cell from making any ABCA12 protein. Other mutations lead to the production of an abnormally small version of the protein that cannot transport lipids properly. A loss of functional ABCA12 protein disrupts the normal development of the epidermis, resulting in the hard, thick scales characteristic of harlequin ichthyosis. |
inheritance | Is harlequin ichthyosis 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. |
treatment | What are the treatments for harlequin ichthyosis ? | These resources address the diagnosis or management of harlequin ichthyosis: - Gene Review: Gene Review: Autosomal Recessive Congenital Ichthyosis - Genetic Testing Registry: Autosomal recessive congenital ichthyosis 4B 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 |
information | What is (are) boomerang dysplasia ? | Boomerang dysplasia is a disorder that affects the development of bones throughout the body. Affected individuals are born with inward- and upward-turning feet (clubfeet) and dislocations of the hips, knees, and elbows. Bones in the spine, rib cage, pelvis, and limbs may be underdeveloped or in some cases absent. As a result of the limb bone abnormalities, individuals with this condition have very short arms and legs. Pronounced bowing of the upper leg bones (femurs) gives them a "boomerang" shape. Some individuals with boomerang dysplasia have a sac-like protrusion of the brain (encephalocele). They may also have an opening in the wall of the abdomen (an omphalocele) that allows the abdominal organs to protrude through the navel. Affected individuals typically have a distinctive nose that is broad with very small nostrils and an underdeveloped partition between the nostrils (septum). Individuals with boomerang dysplasia typically have an underdeveloped rib cage that affects the development and functioning of the lungs. As a result, affected individuals are usually stillborn or die shortly after birth from respiratory failure. |
frequency | How many people are affected by boomerang dysplasia ? | Boomerang dysplasia is a rare disorder; its exact prevalence is unknown. Approximately 10 affected individuals have been identified. |
genetic changes | What are the genetic changes related to boomerang dysplasia ? | Mutations in the FLNB gene cause boomerang dysplasia. The FLNB gene provides instructions for making a protein called filamin B. This protein helps build the network of protein filaments (cytoskeleton) that gives structure to cells and allows them to change shape and move. Filamin B attaches (binds) to another protein called actin and helps the actin to form the branching network of filaments that makes up the cytoskeleton. It also links actin to many other proteins to perform various functions within the cell, including the cell signaling that helps determine how the cytoskeleton will change as tissues grow and take shape during development. Filamin B is especially important in the development of the skeleton before birth. It is active (expressed) in the cell membranes of cartilage-forming cells (chondrocytes). Cartilage is a tough, flexible tissue that makes up much of the skeleton during early development. Most cartilage is later converted to bone (a process called ossification), except for the cartilage that continues to cover and protect the ends of bones and is present in the nose, airways (trachea and bronchi), and external ears. Filamin B appears to be important for normal cell growth and division (proliferation) and maturation (differentiation) of chondrocytes and for the ossification of cartilage. FLNB gene mutations that cause boomerang dysplasia change single protein building blocks (amino acids) in the filamin B protein or delete a small section of the protein sequence, resulting in an abnormal protein. This abnormal protein appears to have a new, atypical function that interferes with the proliferation or differentiation of chondrocytes, impairing ossification and leading to the signs and symptoms of boomerang dysplasia. |
inheritance | Is boomerang dysplasia 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. Almost all cases result from new mutations in the gene and occur in people with no history of the disorder in their family. |
treatment | What are the treatments for boomerang dysplasia ? | These resources address the diagnosis or management of boomerang dysplasia: - Gene Review: Gene Review: FLNB-Related Disorders - Genetic Testing Registry: Boomerang dysplasia 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 |
information | What is (are) dihydrolipoamide dehydrogenase deficiency ? | Dihydrolipoamide dehydrogenase deficiency is a severe condition that can affect several body systems. Signs and symptoms of this condition usually appear shortly after birth, and they can vary widely among affected individuals. A common feature of dihydrolipoamide dehydrogenase deficiency is a potentially life-threatening buildup of lactic acid in tissues (lactic acidosis), which can cause nausea, vomiting, severe breathing problems, and an abnormal heartbeat. Neurological problems are also common in this condition; the first symptoms in affected infants are often decreased muscle tone (hypotonia) and extreme tiredness (lethargy). As the problems worsen, affected infants can have difficulty feeding, decreased alertness, and seizures. Liver problems can also occur in dihydrolipoamide dehydrogenase deficiency, ranging from an enlarged liver (hepatomegaly) to life-threatening liver failure. In some affected people, liver disease, which can begin anytime from infancy to adulthood, is the primary symptom. The liver problems are usually associated with recurrent vomiting and abdominal pain. Rarely, people with dihydrolipoamide dehydrogenase deficiency experience weakness of the muscles used for movement (skeletal muscles), particularly during exercise; droopy eyelids; or a weakened heart muscle (cardiomyopathy). Other features of this condition include excess ammonia in the blood (hyperammonemia), a buildup of molecules called ketones in the body (ketoacidosis), or low blood sugar levels (hypoglycemia). Typically, the signs and symptoms of dihydrolipoamide dehydrogenase deficiency occur in episodes that may be triggered by fever, injury, or other stresses on the body. Affected individuals are usually symptom-free between episodes. Many infants with this condition do not survive the first few years of life because of the severity of these episodes. Affected individuals who survive past early childhood often have delayed growth and neurological problems, including intellectual disability, muscle stiffness (spasticity), difficulty coordinating movements (ataxia), and seizures. |
frequency | How many people are affected by dihydrolipoamide dehydrogenase deficiency ? | Dihydrolipoamide dehydrogenase deficiency occurs in an estimated 1 in 35,000 to 48,000 individuals of Ashkenazi Jewish descent. This population typically has liver disease as the primary symptom. In other populations, the prevalence of dihydrolipoamide dehydrogenase deficiency is unknown, but the condition is likely rare. |
genetic changes | What are the genetic changes related to dihydrolipoamide dehydrogenase deficiency ? | Mutations in the DLD gene cause dihydrolipoamide dehydrogenase deficiency. This gene provides instructions for making an enzyme called dihydrolipoamide dehydrogenase (DLD). DLD is one component of three different groups of enzymes that work together (enzyme complexes): branched-chain alpha-keto acid dehydrogenase (BCKD), pyruvate dehydrogenase (PDH), and alpha ()-ketoglutarate dehydrogenase (KGDH). The BCKD enzyme complex is involved in the breakdown of three protein building blocks (amino acids) commonly found in protein-rich foods: leucine, isoleucine, and valine. Breakdown of these amino acids produces molecules that can be used for energy. The PDH and KGDH enzyme complexes are involved in other reactions in the pathways that convert the energy from food into a form that cells can use. Mutations in the DLD gene impair the function of the DLD enzyme, which prevents the three enzyme complexes from functioning properly. As a result, molecules that are normally broken down and their byproducts build up in the body, damaging tissues and leading to lactic acidosis and other chemical imbalances. In addition, the production of cellular energy is diminished. The brain is especially affected by the buildup of molecules and the lack of cellular energy, resulting in the neurological problems associated with dihydrolipoamide dehydrogenase deficiency. Liver problems are likely also related to decreased energy production in cells. The degree of impairment of each complex contributes to the variability in the features of this condition. |
inheritance | Is dihydrolipoamide dehydrogenase 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. |
treatment | What are the treatments for dihydrolipoamide dehydrogenase deficiency ? | These resources address the diagnosis or management of dihydrolipoamide dehydrogenase deficiency: - Gene Review: Gene Review: Dihydrolipoamide Dehydrogenase Deficiency - Genetic Testing Registry: Maple syrup urine disease, type 3 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 |
information | What is (are) spinal muscular atrophy ? | Spinal muscular atrophy is a genetic disorder that affects the control of muscle movement. It is caused by a loss of specialized nerve cells, called motor neurons, in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). The loss of motor neurons leads to weakness and wasting (atrophy) of muscles used for activities such as crawling, walking, sitting up, and controlling head movement. In severe cases of spinal muscular atrophy, the muscles used for breathing and swallowing are affected. There are many types of spinal muscular atrophy distinguished by the pattern of features, severity of muscle weakness, and age when the muscle problems begin. Type I spinal muscular atrophy (also called Werdnig-Hoffman disease) is a severe form of the disorder that is evident at birth or within the first few months of life. Affected infants are developmentally delayed; most are unable to support their head or sit unassisted. Children with this type have breathing and swallowing problems that may lead to choking or gagging. Type II spinal muscular atrophy is characterized by muscle weakness that develops in children between ages 6 and 12 months. Children with type II can sit without support, although they may need help getting to a seated position. Individuals with this type of spinal muscular atrophy cannot stand or walk unaided. Type III spinal muscular atrophy (also called Kugelberg-Welander disease or juvenile type) has milder features that typically develop between early childhood and adolescence. Individuals with type III spinal muscular atrophy can stand and walk unaided, but walking and climbing stairs may become increasingly difficult. Many affected individuals will require wheelchair assistance later in life. The signs and symptoms of type IV spinal muscular atrophy often occur after age 30. Affected individuals usually experience mild to moderate muscle weakness, tremor, twitching, or mild breathing problems. Typically, only muscles close to the center of the body (proximal muscles), such as the upper arms and legs, are affected in type IV spinal muscular atrophy. The features of X-linked spinal muscular atrophy appear in infancy and include severe muscle weakness and difficulty breathing. Children with this type often have joint deformities (contractures) that impair movement. In severe cases, affected infants are born with broken bones. Poor muscle tone before birth may contribute to the contractures and broken bones seen in these children. Spinal muscular atrophy, lower extremity, dominant (SMA-LED) is characterized by leg muscle weakness that is most severe in the thigh muscles (quadriceps). This weakness begins in infancy or early childhood and progresses slowly. Affected individuals often have a waddling or unsteady walk and have difficulty rising from a seated position and climbing stairs. An adult-onset form of spinal muscular atrophy that begins in early to mid-adulthood affects the proximal muscles and is characterized by muscle cramping of the limbs and abdomen, weakness in the leg muscles, involuntary muscle contractions, tremors, and a protrusion of the abdomen thought to be related to muscle weakness. Some affected individuals experience difficulty swallowing and problems with bladder and bowel function. |
frequency | How many people are affected by spinal muscular atrophy ? | Spinal muscular atrophy affects 1 in 6,000 to 1 in 10,000 people. |
genetic changes | What are the genetic changes related to spinal muscular atrophy ? | Mutations in the SMN1, UBA1, DYNC1H1, and VAPB genes cause spinal muscular atrophy. Extra copies of the SMN2 gene modify the severity of spinal muscular atrophy. The SMN1 and SMN2 genes provide instructions for making a protein called the survival motor neuron (SMN) protein. The SMN protein is important for the maintenance of specialized nerve cells called motor neurons. Motor neurons are located in the spinal cord and the brainstem; they control muscle movement. Most functional SMN protein is produced from the SMN1 gene, with a small amount produced from the SMN2 gene. Several different versions of the SMN protein are produced from the SMN2 gene, but only one version is full size and functional. Mutations in the SMN1 gene cause spinal muscular atrophy types I, II, III, and IV. SMN1 gene mutations lead to a shortage of the SMN protein. Without SMN protein, motor neurons die, and nerve impulses are not passed between the brain and muscles. As a result, some muscles cannot perform their normal functions, leading to weakness and impaired movement. Some people with type II, III, or IV spinal muscular atrophy have three or more copies of the SMN2 gene in each cell. Having multiple copies of the SMN2 gene can modify the course of spinal muscular atrophy. The additional SMN proteins produced from the extra copies of the SMN2 gene can help replace some of the SMN protein that is lost due to mutations in the SMN1 gene. In general, symptoms are less severe and begin later in life as the number of copies of the SMN2 gene increases. Mutations in the UBA1 gene cause X-linked spinal muscular atrophy. The UBA1 gene provides instructions for making the ubiquitin-activating enzyme E1. This enzyme is involved in a process that targets proteins to be broken down (degraded) within cells. UBA1 gene mutations lead to reduced or absent levels of functional enzyme, which disrupts the process of protein degradation. A buildup of proteins in the cell can cause it to die; motor neurons are particularly susceptible to damage from protein buildup. The DYNC1H1 gene provides instructions for making a protein that is part of a group (complex) of proteins called dynein. This complex is found in the fluid inside cells (cytoplasm), where it is part of a network that moves proteins and other materials. In neurons, dynein moves cellular materials away from the junctions between neurons (synapses) to the center of the cell. This process helps transmit chemical messages from one neuron to another. DYNC1H1 gene mutations that cause SMA-LED disrupt the function of the dynein complex. As a result, the movement of proteins, cellular structures, and other materials within cells are impaired. A decrease in chemical messaging between neurons that control muscle movement is thought to contribute to the muscle weakness experienced by people with SMA-LED. It is unclear why this condition affects only the lower extremities. The adult-onset form of spinal muscular atrophy is caused by a mutation in the VAPB gene. The VAPB gene provides instructions for making a protein that is found in cells throughout the body. Researchers suggest that this protein may play a role in preventing the buildup of unfolded or misfolded proteins within cells. It is unclear how a VAPB gene mutation leads to the loss of motor neurons. An impaired VAPB protein might cause misfolded and unfolded proteins to accumulate and impair the normal function of motor neurons. Other types of spinal muscular atrophy that primarily affect the lower legs and feet and the lower arms and hands are caused by the dysfunction of neurons in the spinal cord. When spinal muscular atrophy shows this pattern of signs and symptoms, it is also known as distal hereditary motor neuropathy. The various types of this condition are caused by mutations in other genes. |
inheritance | Is spinal muscular atrophy inherited ? | Types I, II, III, and IV spinal muscular atrophy are inherited in an autosomal recessive pattern, which means both copies of the SMN1 gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. Extra copies of the SMN2 gene are due to a random error when making new copies of DNA (replication) in an egg or sperm cell or just after fertilization. SMA-LED and the late-onset form of spinal muscular atrophy caused by VAPB gene mutations are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. X-linked spinal muscular atrophy is inherited in an X-linked pattern. The UBA1 gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for spinal muscular atrophy ? | These resources address the diagnosis or management of spinal muscular atrophy: - Gene Review: Gene Review: Spinal Muscular Atrophy - Gene Review: Gene Review: Spinal Muscular Atrophy, X-Linked Infantile - Genetic Testing Registry: Adult proximal spinal muscular atrophy, autosomal dominant - Genetic Testing Registry: Arthrogryposis multiplex congenita, distal, X-linked - Genetic Testing Registry: Kugelberg-Welander disease - Genetic Testing Registry: Spinal muscular atrophy type 4 - Genetic Testing Registry: Spinal muscular atrophy, lower extremity predominant 1, autosomal dominant - Genetic Testing Registry: Spinal muscular atrophy, type II - Genetic Testing Registry: Werdnig-Hoffmann disease - Genomics Education Programme (UK) - MedlinePlus Encyclopedia: Spinal Muscular Atrophy These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) ankyloblepharon-ectodermal defects-cleft lip/palate syndrome ? | Ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome is a form of ectodermal dysplasia, a group of about 150 conditions characterized by abnormal development of ectodermal tissues including the skin, hair, nails, teeth, and sweat glands. Among the most common features of AEC syndrome are missing patches of skin (erosions). In affected infants, skin erosions most commonly occur on the scalp. They tend to recur throughout childhood and into adulthood, frequently affecting the scalp, neck, hands, and feet. The skin erosions range from mild to severe and can lead to infection, scarring, and hair loss. Other ectodermal abnormalities in AEC syndrome include changes in skin coloring; brittle, sparse, or missing hair; misshapen or absent fingernails and toenails; and malformed or missing teeth. Affected individuals also report increased sensitivity to heat and a reduced ability to sweat. Many infants with AEC syndrome are born with an eyelid condition known as ankyloblepharon filiforme adnatum, in which strands of tissue partially or completely fuse the upper and lower eyelids. Most people with AEC syndrome are also born with an opening in the roof of the mouth (a cleft palate), a split in the lip (a cleft lip), or both. Cleft lip or cleft palate can make it difficult for affected infants to suck, so these infants often have trouble feeding and do not grow and gain weight at the expected rate (failure to thrive). Additional features of AEC syndrome can include limb abnormalities, most commonly fused fingers and toes (syndactyly). Less often, affected individuals have permanently bent fingers and toes (camptodactyly) or a deep split in the hands or feet with missing fingers or toes and fusion of the remaining digits (ectrodactyly). Hearing loss is common, occurring in more than 90 percent of children with AEC syndrome. Some affected individuals have distinctive facial features, such as small jaws that cannot open fully and a narrow space between the upper lip and nose (philtrum). Other signs and symptoms can include the opening of the urethra on the underside of the penis (hypospadias) in affected males, digestive problems, absent tear duct openings in the eyes, and chronic sinus or ear infections. A condition known as Rapp-Hodgkin syndrome has signs and symptoms that overlap considerably with those of AEC syndrome. These two syndromes were classified as separate disorders until it was discovered that they both result from mutations in the same part of the same gene. Most researchers now consider Rapp-Hodgkin syndrome and AEC syndrome to be part of the same disease spectrum. |
frequency | How many people are affected by ankyloblepharon-ectodermal defects-cleft lip/palate syndrome ? | AEC syndrome is a rare condition; its prevalence is unknown. All forms of ectodermal dysplasia together occur in about 1 in 100,000 newborns in the United States. |
genetic changes | What are the genetic changes related to ankyloblepharon-ectodermal defects-cleft lip/palate syndrome ? | AEC syndrome is caused by mutations in the TP63 gene. This gene provides instructions for making a protein known as p63, which plays an essential role in early development. The p63 protein is a transcription factor, which means that it attaches (binds) to DNA and controls the activity of particular genes. The p63 protein turns many different genes on and off during development. It appears to be especially critical for the development of ectodermal structures, such as the skin, hair, teeth, and nails. Studies suggest that it also plays important roles in the development of the limbs, facial features, urinary system, and other organs and tissues. The TP63 gene mutations responsible for AEC syndrome interfere with the ability of p63 to turn target genes on and off at the right times. It is unclear how these changes lead to abnormal ectodermal development and the specific features of AEC syndrome. |
inheritance | Is ankyloblepharon-ectodermal defects-cleft lip/palate 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. |
treatment | What are the treatments for ankyloblepharon-ectodermal defects-cleft lip/palate syndrome ? | These resources address the diagnosis or management of AEC syndrome: - Gene Review: Gene Review: TP63-Related Disorders - Genetic Testing Registry: Hay-Wells syndrome of ectodermal dysplasia - Genetic Testing Registry: Rapp-Hodgkin ectodermal dysplasia 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 |
information | What is (are) pyridoxine-dependent epilepsy ? | Pyridoxine-dependent epilepsy is a condition that involves seizures beginning in infancy or, in some cases, before birth. Those affected typically experience prolonged seizures lasting several minutes (status epilepticus). These seizures involve muscle rigidity, convulsions, and loss of consciousness (tonic-clonic seizures). Additional features of pyridoxine-dependent epilepsy include low body temperature (hypothermia), poor muscle tone (dystonia) soon after birth, and irritability before a seizure episode. In rare instances, children with this condition do not have seizures until they are 1 to 3 years old. Anticonvulsant drugs, which are usually given to control seizures, are ineffective in people with pyridoxine-dependent epilepsy. Instead, people with this type of seizure are medically treated with large daily doses of pyridoxine (a type of vitamin B6 found in food). If left untreated, people with this condition can develop severe brain dysfunction (encephalopathy). Even though seizures can be controlled with pyridoxine, neurological problems such as developmental delay and learning disorders may still occur. |
frequency | How many people are affected by pyridoxine-dependent epilepsy ? | Pyridoxine-dependent epilepsy occurs in 1 in 100,000 to 700,000 individuals. At least 100 cases have been reported worldwide. |
genetic changes | What are the genetic changes related to pyridoxine-dependent epilepsy ? | Mutations in the ALDH7A1 gene cause pyridoxine-dependent epilepsy. The ALDH7A1 gene provides instructions for making an enzyme called -aminoadipic semialdehyde (-AASA) dehydrogenase, also known as antiquitin. This enzyme is involved in the breakdown of the protein building block (amino acid) lysine in the brain. When antiquitin is deficient, a molecule that interferes with vitamin B6 function builds up in various tissues. Pyridoxine plays a role in many processes in the body, such as the breakdown of amino acids and the productions of chemicals that transmit signals in the brain (neurotransmitters). It is unclear how a lack of pyridoxine causes the seizures that are characteristic of this condition. Some individuals with pyridoxine-dependent epilepsy do not have identified mutations in the ALDH7A1 gene. In these cases, the cause of the condition is unknown. |
inheritance | Is pyridoxine-dependent epilepsy 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. |
treatment | What are the treatments for pyridoxine-dependent epilepsy ? | These resources address the diagnosis or management of pyridoxine-dependent epilepsy: - Gene Review: Gene Review: Pyridoxine-Dependent Epilepsy - Genetic Testing Registry: Pyridoxine-dependent epilepsy - MedlinePlus Encyclopedia: Generalized tonic-clonic seizure 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 |
information | What is (are) Wiskott-Aldrich syndrome ? | Wiskott-Aldrich syndrome is characterized by abnormal immune system function (immune deficiency) and a reduced ability to form blood clots. This condition primarily affects males. Individuals with Wiskott-Aldrich syndrome have microthrombocytopenia, which is a decrease in the number and size of blood cells involved in clotting (platelets). This platelet abnormality, which is typically present from birth, can lead to easy bruising or episodes of prolonged bleeding following minor trauma. Wiskott-Aldrich syndrome causes many types of white blood cells, which are part of the immune system, to be abnormal or nonfunctional, leading to an increased risk of several immune and inflammatory disorders. Many people with this condition develop eczema, an inflammatory skin disorder characterized by abnormal patches of red, irritated skin. Affected individuals also have an increased susceptibility to infection. People with Wiskott-Aldrich syndrome are at greater risk of developing autoimmune disorders, which occur when the immune system malfunctions and attacks the body's own tissues and organs. The chance of developing some types of cancer, such as cancer of the immune system cells (lymphoma), is also greater in people with Wiskott-Aldrich syndrome. |
frequency | How many people are affected by Wiskott-Aldrich syndrome ? | The estimated incidence of Wiskott-Aldrich syndrome is between 1 and 10 cases per million males worldwide; this condition is rarer in females. |
genetic changes | What are the genetic changes related to Wiskott-Aldrich syndrome ? | Mutations in the WAS gene cause Wiskott-Aldrich syndrome. The WAS gene provides instructions for making a protein called WASP. This protein is found in all blood cells. WASP is involved in relaying signals from the surface of blood cells to the actin cytoskeleton, which is a network of fibers that make up the cell's structural framework. WASP signaling activates the cell when it is needed and triggers its movement and attachment to other cells and tissues (adhesion). In white blood cells, this signaling allows the actin cytoskeleton to establish the interaction between cells and the foreign invaders that they target (immune synapse). WAS gene mutations that cause Wiskott-Aldrich syndrome lead to a lack of any functional WASP. Loss of WASP signaling disrupts the function of the actin cytoskeleton in developing blood cells. White blood cells that lack WASP have a decreased ability to respond to their environment and form immune synapses. As a result, white blood cells are less able to respond to foreign invaders, causing many of the immune problems related to Wiskott-Aldrich syndrome. Similarly, a lack of functional WASP in platelets impairs their development, leading to reduced size and early cell death. |
inheritance | Is Wiskott-Aldrich syndrome inherited ? | This condition is inherited in an X-linked pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In females (who have two X chromosomes), a mutation in one of the two copies of the gene in each cell may or may not cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of the gene in each cell causes the disorder. In most cases of X-linked inheritance, males experience more severe symptoms of the disorder than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for Wiskott-Aldrich syndrome ? | These resources address the diagnosis or management of Wiskott-Aldrich syndrome: - Gene Review: Gene Review: WAS-Related Disorders - Genetic Testing Registry: Wiskott-Aldrich syndrome - MedlinePlus Encyclopedia: Thrombocytopenia - National Marrow Donor Program - Rare Disease Clinical Research Network: Primary Immune Deficiency Treatment Consortium 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 |
information | What is (are) short QT syndrome ? | Short QT syndrome is a condition that can cause a disruption of the heart's normal rhythm (arrhythmia). In people with this condition, the heart (cardiac) muscle takes less time than usual to recharge between beats. The term "short QT" refers to a specific pattern of heart activity that is detected with an electrocardiogram (EKG), which is a test used to measure the electrical activity of the heart. In people with this condition, the part of the heartbeat known as the QT interval is abnormally short. If untreated, the arrhythmia associated with short QT syndrome can lead to a variety of signs and symptoms, from dizziness and fainting (syncope) to cardiac arrest and sudden death. These signs and symptoms can occur any time from early infancy to old age. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of unexplained death in babies younger than 1 year. However, some people with short QT syndrome never experience any health problems associated with the condition. |
frequency | How many people are affected by short QT syndrome ? | Short QT syndrome appears to be rare. At least 70 cases have been identified worldwide since the condition was discovered in 2000. However, the condition may be underdiagnosed because some affected individuals never experience symptoms. |
genetic changes | What are the genetic changes related to short QT syndrome ? | Mutations in the KCNH2, KCNJ2, and KCNQ1 genes can cause short QT syndrome. These genes provide instructions for making channels that transport positively charged atoms (ions) of potassium out of cells. In cardiac muscle, these ion channels play critical roles in maintaining the heart's normal rhythm. Mutations in the KCNH2, KCNJ2, or KCNQ1 gene increase the activity of the channels, which enhances the flow of potassium ions across the membrane of cardiac muscle cells. This change in ion transport alters the electrical activity of the heart and can lead to the abnormal heart rhythms characteristic of short QT syndrome. Some affected individuals do not have an identified mutation in the KCNH2, KCNJ2, or KCNQ1 gene. Changes in other genes that have not been identified may cause the disorder in these cases. |
inheritance | Is short QT syndrome inherited ? | Short QT syndrome appears to have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Some affected individuals have a family history of short QT syndrome or related heart problems and sudden cardiac death. Other cases of short QT syndrome are classified as sporadic and occur in people with no apparent family history of related heart problems. |
treatment | What are the treatments for short QT syndrome ? | These resources address the diagnosis or management of short QT syndrome: - Genetic Testing Registry: Short QT syndrome 1 - Genetic Testing Registry: Short QT syndrome 2 - Genetic Testing Registry: Short QT syndrome 3 - MedlinePlus Encyclopedia: Arrhythmias 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 |
information | What is (are) spinal muscular atrophy with respiratory distress type 1 ? | Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is an inherited condition that causes muscle weakness and respiratory failure typically beginning in infancy. Early features of this condition are difficult and noisy breathing, especially when inhaling; a weak cry; problems feeding; and recurrent episodes of pneumonia. Typically between the ages of 6 weeks and 6 months, infants with this condition will experience a sudden inability to breathe due to paralysis of the muscle that separates the abdomen from the chest cavity (the diaphragm). Normally, the diaphragm contracts and moves downward during inhalation to allow the lungs to expand. With diaphragm paralysis, affected individuals require life-long support with a machine to help them breathe (mechanical ventilation). Rarely, children with SMARD1 develop signs or symptoms of the disorder later in childhood. Soon after respiratory failure occurs, individuals with SMARD1 develop muscle weakness in their distal muscles. These are the muscles farther from the center of the body, such as muscles in the hands and feet. The weakness soon spreads to all muscles; however, within 2 years, the muscle weakness typically stops getting worse. Some individuals may retain a low level of muscle function, while others lose all ability to move their muscles. Muscle weakness severely impairs motor development, such as sitting, standing, and walking. Some affected children develop an abnormal side-to-side and back-to-front curvature of the spine (scoliosis and kyphosis, often called kyphoscoliosis when they occur together). After approximately the first year of life, individuals with SMARD1 may lose their deep tendon reflexes, such as the reflex being tested when a doctor taps the knee with a hammer. Other features of SMARD1 can include reduced pain sensitivity, excessive sweating (hyperhidrosis), loss of bladder and bowel control, and an irregular heartbeat (arrhythmia). |
frequency | How many people are affected by spinal muscular atrophy with respiratory distress type 1 ? | SMARD1 appears to be a rare condition, but its prevalence is unknown. More than 60 cases have been reported in the scientific literature. |
genetic changes | What are the genetic changes related to spinal muscular atrophy with respiratory distress type 1 ? | Mutations in the IGHMBP2 gene cause SMARD1. The IGHMBP2 gene provides instructions for making a protein involved in copying (replicating) DNA; producing RNA, a chemical cousin of DNA; and producing proteins. IGHMBP2 gene mutations that cause SMARD1 lead to the production of a protein with reduced ability to aid in DNA replication and the production of RNA and proteins. These problems particularly affect alpha-motor neurons, which are specialized cells in the brainstem and spinal cord that control muscle movements. Although the mechanism is unknown, altered IGHMBP2 proteins contribute to the damage of these neurons and their death over time. The cumulative death of alpha-motor neurons leads to breathing problems and progressive muscle weakness in children with SMARD1. Research suggests that the amount of functional protein that is produced from the mutated IGHMBP2 gene may play a role in the severity of SMARD1. Individuals who have some functional protein are more likely to develop signs and symptoms later in childhood and retain a greater level of muscle function. |
inheritance | Is spinal muscular atrophy with respiratory distress type 1 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. |
treatment | What are the treatments for spinal muscular atrophy with respiratory distress type 1 ? | These resources address the diagnosis or management of SMARD1: - Genetic Testing Registry: Spinal muscular atrophy with respiratory distress 1 These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) pseudocholinesterase deficiency ? | Pseudocholinesterase deficiency is a condition that results in increased sensitivity to certain muscle relaxant drugs used during general anesthesia, called choline esters. These fast-acting drugs, such as succinylcholine and mivacurium, are given to relax the muscles used for movement (skeletal muscles), including the muscles involved in breathing. The drugs are often employed for brief surgical procedures or in emergencies when a breathing tube must be inserted quickly. Normally, these drugs are broken down (metabolized) by the body within a few minutes of being administered, at which time the muscles can move again. However, people with pseudocholinesterase deficiency may not be able to move or breathe on their own for a few hours after the drugs are administered. Affected individuals must be supported with a machine to help them breathe (mechanical ventilation) until the drugs are cleared from the body. People with pseudocholinesterase deficiency may also have increased sensitivity to certain other drugs, including the local anesthetic procaine, and to specific agricultural pesticides. The condition causes no other signs or symptoms and is usually not discovered until an abnormal drug reaction occurs. |
frequency | How many people are affected by pseudocholinesterase deficiency ? | Pseudocholinesterase deficiency occurs in 1 in 3,200 to 1 in 5,000 people. It is more common in certain populations, such as the Persian Jewish community and Alaska Natives. |
genetic changes | What are the genetic changes related to pseudocholinesterase deficiency ? | Pseudocholinesterase deficiency can be caused by mutations in the BCHE gene. This gene provides instructions for making the pseudocholinesterase enzyme, also known as butyrylcholinesterase, which is produced by the liver and circulates in the blood. The pseudocholinesterase enzyme is involved in the breakdown of choline ester drugs. It is likely that the enzyme has other functions in the body, but these functions are not well understood. Studies suggest that the enzyme may be involved in the transmission of nerve signals. Some BCHE gene mutations that cause pseudocholinesterase deficiency result in an abnormal pseudocholinesterase enzyme that does not function properly. Other mutations prevent the production of the pseudocholinesterase enzyme. A lack of functional pseudocholinesterase enzyme impairs the body's ability to break down choline ester drugs efficiently, leading to abnormally prolonged drug effects. Pseudocholinesterase deficiency can also have nongenetic causes. In these cases, the condition is called acquired pseudocholinesterase deficiency; it is not inherited and cannot be passed to the next generation. Activity of the pseudocholinesterase enzyme can be impaired by kidney or liver disease, malnutrition, major burns, cancer, or certain drugs. |
inheritance | Is pseudocholinesterase deficiency inherited ? | When due to genetic causes, this condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive disorder have one copy of the altered gene in each cell and are called carriers. They can pass on the gene mutation to their children, but they do not usually experience signs and symptoms of the disorder. In some cases, carriers of BCHE gene mutations take longer than usual to clear choline ester drugs from the body, but not as long as those with two copies of the altered gene in each cell. |
treatment | What are the treatments for pseudocholinesterase deficiency ? | These resources address the diagnosis or management of pseudocholinesterase deficiency: - MedlinePlus Encyclopedia: Cholinesterase (blood test) These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Tourette syndrome ? | Tourette syndrome is a complex disorder characterized by repetitive, sudden, and involuntary movements or noises called tics. Tics usually appear in childhood, and their severity varies over time. In most cases, tics become milder and less frequent in late adolescence and adulthood. Tourette syndrome involves both motor tics, which are uncontrolled body movements, and vocal or phonic tics, which are outbursts of sound. Some motor tics are simple and involve only one muscle group. Simple motor tics, such as rapid eye blinking, shoulder shrugging, or nose twitching, are usually the first signs of Tourette syndrome. Motor tics also can be complex (involving multiple muscle groups), such as jumping, kicking, hopping, or spinning. Vocal tics, which generally appear later than motor tics, also can be simple or complex. Simple vocal tics include grunting, sniffing, and throat-clearing. More complex vocalizations include repeating the words of others (echolalia) or repeating one's own words (palilalia). The involuntary use of inappropriate or obscene language (coprolalia) is possible, but uncommon, among people with Tourette syndrome. In addition to frequent tics, people with Tourette syndrome are at risk for associated problems including attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, depression, and problems with sleep. |
frequency | How many people are affected by Tourette syndrome ? | Although the exact incidence of Tourette syndrome is uncertain, it is estimated to affect 1 to 10 in 1,000 children. This disorder occurs in populations and ethnic groups worldwide, and it is more common in males than in females. |
genetic changes | What are the genetic changes related to Tourette syndrome ? | A variety of genetic and environmental factors likely play a role in causing Tourette syndrome. Most of these factors are unknown, and researchers are studying risk factors before and after birth that may contribute to this complex disorder. Scientists believe that tics may result from changes in brain chemicals (neurotransmitters) that are responsible for producing and controlling voluntary movements. Mutations involving the SLITRK1 gene have been identified in a small number of people with Tourette syndrome. This gene provides instructions for making a protein that is active in the brain. The SLITRK1 protein probably plays a role in the development of nerve cells, including the growth of specialized extensions (axons and dendrites) that allow each nerve cell to communicate with nearby cells. It is unclear how mutations in the SLITRK1 gene can lead to this disorder. Most people with Tourette syndrome do not have a mutation in the SLITRK1 gene. Because mutations have been reported in so few people with this condition, the association of the SLITRK1 gene with this disorder has not been confirmed. Researchers suspect that changes in other genes, which have not been identified, are also associated with Tourette syndrome. |
inheritance | Is Tourette syndrome inherited ? | The inheritance pattern of Tourette syndrome is unclear. Although the features of this condition can cluster in families, many genetic and environmental factors are likely to be involved. Among family members of an affected person, it is difficult to predict who else may be at risk of developing the condition. Tourette syndrome was previously thought to have an autosomal dominant pattern of inheritance, which suggests that one mutated copy of a gene in each cell would be sufficient to cause the condition. Several decades of research have shown that this is not the case. Almost all cases of Tourette syndrome probably result from a variety of genetic and environmental factors, not changes in a single gene. |
treatment | What are the treatments for Tourette syndrome ? | These resources address the diagnosis or management of Tourette syndrome: - Gene Review: Gene Review: Tourette Disorder Overview - Genetic Testing Registry: Tourette Syndrome - MedlinePlus Encyclopedia: Gilles de la Tourette 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 |
information | What is (are) fibrodysplasia ossificans progressiva ? | Fibrodysplasia ossificans progressiva (FOP) is a disorder in which muscle tissue and connective tissue such as tendons and ligaments are gradually replaced by bone (ossified), forming bone outside the skeleton (extra-skeletal or heterotopic bone) that constrains movement. This process generally becomes noticeable in early childhood, starting with the neck and shoulders and proceeding down the body and into the limbs. Extra-skeletal bone formation causes progressive loss of mobility as the joints become affected. Inability to fully open the mouth may cause difficulty in speaking and eating. Over time, people with this disorder may experience malnutrition due to their eating problems. They may also have breathing difficulties as a result of extra bone formation around the rib cage that restricts expansion of the lungs. Any trauma to the muscles of an individual with fibrodysplasia ossificans progressiva, such as a fall or invasive medical procedures, may trigger episodes of muscle swelling and inflammation (myositis) followed by more rapid ossification in the injured area. Flare-ups may also be caused by viral illnesses such as influenza. People with fibrodysplasia ossificans progressiva are generally born with malformed big toes. This abnormality of the big toes is a characteristic feature that helps to distinguish this disorder from other bone and muscle problems. Affected individuals may also have short thumbs and other skeletal abnormalities. |
frequency | How many people are affected by fibrodysplasia ossificans progressiva ? | Fibrodysplasia ossificans progressiva is a very rare disorder, believed to occur in approximately 1 in 2 million people worldwide. Several hundred cases have been reported. |
genetic changes | What are the genetic changes related to fibrodysplasia ossificans progressiva ? | Mutations in the ACVR1 gene cause fibrodysplasia ossificans progressiva. The ACVR1 gene provides instructions for producing a member of a protein family called bone morphogenetic protein (BMP) type I receptors. The ACVR1 protein is found in many tissues of the body including skeletal muscle and cartilage. It helps to control the growth and development of the bones and muscles, including the gradual replacement of cartilage by bone (ossification) that occurs in normal skeletal maturation from birth to young adulthood. Researchers believe that a mutation in the ACVR1 gene may change the shape of the receptor under certain conditions and disrupt mechanisms that control the receptor's activity. As a result, the receptor may be constantly turned on (constitutive activation). Constitutive activation of the receptor causes overgrowth of bone and cartilage and fusion of joints, resulting in the signs and symptoms of fibrodysplasia ossificans progressiva. |
inheritance | Is fibrodysplasia ossificans progressiva 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. Most cases of fibrodysplasia ossificans progressiva result from new mutations in the gene. These cases occur in people with no history of the disorder in their family. In a small number of cases, an affected person has inherited the mutation from one affected parent. |
treatment | What are the treatments for fibrodysplasia ossificans progressiva ? | These resources address the diagnosis or management of fibrodysplasia ossificans progressiva: - Genetic Testing Registry: Progressive myositis ossificans 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 |
information | What is (are) adenosine monophosphate deaminase deficiency ? | Adenosine monophosphate (AMP) deaminase deficiency is a condition that can affect the muscles used for movement (skeletal muscles). People with this condition do not make enough of an enzyme called AMP deaminase. In most people, AMP deaminase deficiency does not cause any symptoms. People who do experience symptoms typically have muscle pain (myalgia) or weakness after exercise or prolonged physical activity. They often get tired more quickly and stay tired longer than would normally be expected. Some affected individuals have more severe symptoms, but it is unclear whether these symptoms are due solely to a lack of AMP deaminase or additional factors. Muscle weakness is typically apparent beginning in childhood or early adulthood. Researchers have proposed three types of AMP deaminase deficiency, which are distinguished by their symptoms and genetic cause. |
frequency | How many people are affected by adenosine monophosphate deaminase deficiency ? | AMP deaminase deficiency is one of the most common inherited muscle disorders in white populations, affecting 1 in 50 to 100 people. The prevalence is lower in African Americans, affecting an estimated 1 in 40,000 people, and the condition is even less common in the Japanese population. |
genetic changes | What are the genetic changes related to adenosine monophosphate deaminase deficiency ? | Mutations in the AMPD1 gene cause AMP deaminase deficiency. The AMPD1 gene provides instructions for producing an enzyme called AMP deaminase. This enzyme is found in skeletal muscle, where it plays a role in producing energy within muscle cells. Mutations in the AMPD1 gene disrupt the function of AMP deaminase and impair the muscle cells' ability to produce energy. This lack of energy can lead to myalgia or other muscle problems associated with AMP deaminase deficiency. The three types of AMP deaminase deficiency are known as the inherited type, acquired type, and coincidental inherited type. Individuals with the inherited type have a mutation in both copies of the AMPD1 gene in each cell. Most people are asymptomatic, meaning they have no symptoms. Some people with AMP deaminase deficiency experience muscle weakness or pain following exercise. The acquired type occurs in people who have decreased levels of AMP deaminase due to the presence of a muscle or joint condition. People with the coincidental inherited type have a mutation in both copies of the AMPD1 gene. Additionally, they have a separate joint or muscle disorder. Some individuals experience more severe joint or muscle symptoms related to their disorder if they have AMP deaminase deficiency than do people without this enzyme deficiency. Most, however, do not have any symptoms associated with AMP deaminase deficiency. It is not known why most people with this condition do not experience symptoms. Researchers speculate that additional mutations in other genes may be involved. |
inheritance | Is adenosine monophosphate deaminase 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. |
treatment | What are the treatments for adenosine monophosphate deaminase deficiency ? | These resources address the diagnosis or management of adenosine monophosphate deaminase deficiency: - MedlinePlus Encyclopedia: Muscle aches - MedlinePlus Encyclopedia: Weakness 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 |
information | 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. |
frequency | 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. |
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