Congenital contractural arachnodactyly

Congenital contractural arachnodactyly (CCA) is a genetic disorder that is characterized by tall height; skinny, long limbs; long, skinny fingers and toes (arachnodactyly); multiple joint deformities present at birth (congenital contractures), usually of the elbows, knees, hips, fingers and ankles; "crumpled"-looking ears; and curvature of the spine (kyphoscoliosis). Enlargement (dilation) of the aorta and other features might also be present in some affected people.^[1][2][3] CCA is caused by mutations in a gene called FBN2 gene and is inherited in an autosomal dominant pattern.^[1][2] CCA shares similiar signs and symptoms to Marfan syndrome; however, Marfan syndrome is not caused by mutations in the FBN2 gene. Treatment includes physical therapy or surgery for joint contractures, bracing and/or surgery for kyphoscoliosis, and standard management of aortic root dilation.^[1]

The features of congenital contractural arachnodactyly (CCA) vary from person to person, both within and between families. The classic form is characterized by:^[1] 

• Marfan-like appearance (tall and slender with arm span longer than the person's height)
• Arachnodactyly (long slender fingers and toes)
• "Crumpled" ears
• Contractures of major joints from birth (particularly knees, elbows, fingers, toes, and hips)
• Bowed long bones
• Muscular hypoplasia (underdeveloped muscles)
• Kyphosis/scoliosis
• Aortic root dilation
• Craniofacial abnormalities (such as micrognathia; high arched palate; scaphocephaly (premature fusion of the sagittal suture of the skull leading to a long, narrow head); brachycephaly (premature fusion of the coronal suture, leading to a short skull); and frontal bossing).

Severe forms of CCA are very rare, with very few reported cases. In addition to the typical skeletal findings (arachnodactyly, joint contractures, and scoliosis) and abnormally shaped ears, infants with the severe/lethal form have many cardiovascular and gastrointestinal abnormalities.^[1]

Congenital contractural arachnodactyly (CCA) is caused by mutations in the FBN2 gene. 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 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 CCA.^[1]

 

 

Physical therapy for joint contractures helps increase joint mobility and improve the effects of muscle hypoplasia (usually in the calf muscles). In severe cases, surgery may be needed. Since the kyphosis/scoliosis tends to be progressive, bracing and/or surgical correction is often needed. Consultation with an orthopedist is encouraged. Other symptoms, if present, should be addressed as they arise. Regular physician visits should be scheduled to monitor symptom progression and development.^[1]