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Congenital contractural arachnodactyly is a disorder that affects many parts of the body. People with this condition typically are tall with long limbs (dolichostenomelia) and long, slender fingers and toes (arachnodactyly). They often have permanently bent joints (contractures) that can restrict movement in their hips, knees, ankles, or elbows. Additional features of congenital contractural arachnodactyly include underdeveloped muscles, a rounded upper back that also curves to the side (kyphoscoliosis), permanently bent fingers and toes (camptodactyly), ears that look "crumpled," and a protruding chest (pectus carinatum). Rarely, people with congenital contractural arachnodactyly have heart defects such as an enlargement of the blood vessel that distributes blood from the heart to the rest of the body (aortic root dilatation) or a leak in one of the valves that control blood flow through the heart (mitral valve prolapse). The life expectancy of individuals with congenital contractural arachnodactyly varies depending on the severity of symptoms but is typically not shortened.
A rare, severe form of congenital contractural arachnodactyly involves both heart and digestive system abnormalities in addition to the skeletal features described above; individuals with this severe form of the condition usually do not live past infancy.
The prevalence of congenital contractural arachnodactyly is estimated to be less than 1 in 10,000 worldwide.
Mutations in the FBN2 gene cause congenital contractural arachnodactyly. The FBN2 gene provides instructions for producing the fibrillin-2 protein. Fibrillin-2 binds to other proteins and molecules to form threadlike filaments called microfibrils. Microfibrils become part of the fibers that provide strength and flexibility to connective tissue that supports the body's joints and organs. Additionally, microfibrils regulate the activity of molecules called growth factors. Growth factors enable the growth and repair of tissues throughout the body.
Mutations in the FBN2 gene can decrease fibrillin-2 production or result in the production of a protein with impaired function. As a result, microfibril formation is reduced, which probably weakens the structure of connective tissue and disrupts regulation of growth factor activity. The resulting abnormalities of connective tissue underlie the signs and symptoms of congenital contractural arachnodactyly.
Changes in this gene are associated with congenital contractural arachnodactyly.
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 some cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.
These resources address the diagnosis or management of congenital contractural arachnodactyly and may include treatment providers.
You might also find information on the diagnosis or management of congenital contractural arachnodactyly in Educational resources (http://ghr.nlm.nih.gov/condition/congenital-contractural-arachnodactyly/show/Educational+resources) and Patient support (http://ghr.nlm.nih.gov/condition/congenital-contractural-arachnodactyly/show/Patient+support).
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
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You may find the following resources about congenital contractural arachnodactyly helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/gard).
arachnodactyly ; autosomal ; autosomal dominant ; camptodactyly ; cell ; congenital ; connective tissue ; digestive ; digestive system ; dilatation ; distal ; dolichostenomelia ; gene ; growth factor ; inherited ; kyphoscoliosis ; microfibrils ; mitral valve ; mitral valve prolapse ; mutation ; prevalence ; protein ; syndrome ; tissue
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