One form that has been clearly described is Fukuyama congenital muscular dystrophy. This disorder involves severe weakness of the facial and limb muscles and a generalized lack of muscle tone, usually appearing before 9 months. Joint contractures are common. Brain abnormalities are also present, and most children have severe mental and speech problems. Seizures are often part of the disease, and medications are prescribed for these.
Physical therapy is needed to minimize the contractures.
The disease has been linked to a gene defect on chromosome 9, although the precise gene and its protein are so far unknown. Another form of congenital dystrophy seems to be related to a deficiency or malfunction of the protein merosin, which normally lies outside muscle cells and links them to the surrounding tissue. The disorder is similar to Fukuyama dystrophy, with muscle weakness evident at birth or in the first few months of life, severe and early contractures and often joint deformities. This is followed by other signs of eye and facial muscle weakness, as well as by difficulty in swallowing. The later stages of this slowly progressive disease may include weakness in the pelvic and shoulder muscles.