Congenital contractural arachnodactyly

Congenital contractural arachnodactyly is a disorder that affects many parts of the body. People with this condition typically are tall and slender with long limbs (dolichostenomelia), and have long, slender fingers and toes (arachnodactyly); joint deformities (contractures) that restrict movement; and a "crumpled" look to their ears. Additional features of congenital contractural arachnodactyly include underdeveloped muscles, abnormal curvature of the spine (scoliosis), permanently bent fingers and toes (camptodactyly), and a protruding chest (pectus carinatum). Occasionally, people with this condition have heart problems, such as enlargement of the blood vessel that distributes blood from the heart to the rest of the body (dilatation of the aorta) or leaks in one of the valves that control blood flow through the heart (mitral valve regurgitation).

A rare, severe form of congenital contractural arachnodactyly involves heart and digestive system abnormalities in addition to the typical features seen in this condition; those affected typically do not live past infancy.

The incidence of congenital contractural arachnodactyly is estimated to be less than 1 in 10,000.

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. Additionally, microfibrils hold molecules called growth factors and release them at the appropriate time to control the growth and repair of tissues and organs throughout the body. A mutation in the FBN2 gene can reduce the amount and/or quality of fibrillin-2 that is available to form microfibrils. As a result, decreased microfibril formation probably weakens the elastic fibers and allows growth factors to be released inappropriately, causing tall stature, deformities of the fingers and toes, and other characteristic features of congenital contractural arachnodactyly.

Read more about the FBN2 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 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.