Arthrogryposis multiplex congenita

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Arthrogryposis multiplex congenita refers to a variety of conditions that involve congenital limitation of joint movement. Intelligence is typically normal except when the arthrogryposis is caused by a disorder or syndrome that also affects intelligence. Diagnosis is clinical. Treatment includes joint manipulation and casting and sometimes surgery.
(See also Introduction to Congenital Craniofacial and Musculoskeletal Disorders.)
Arthrogryposis is not a specific diagnosis but rather a clinical finding of congenital contractures; these may be present in gt; 300 different disorders. Prevalence varies in different studies between about 1/3,000 to 1/12,000 live births. The perinatal mortality for some of the underlying conditions is as high as 32%, so establishing a specific diagnosis is important for prognosis and genetic counseling.
There are two major types of arthrogryposis multiplex congenita (AMC):

Amyoplasia (classic arthrogryposis): Multiple symmetric contractures occur in the limbs. Affected muscles are hypoplastic and have fibrous and fatty degeneration. Usually intelligence is normal. About 10% of patients have abdominal abnormalities (eg, gastroschisis, bowel atresia) due to a lack of muscle formation. Nearly all cases are sporadic.
Distal arthrogryposis: The hands and feet are involved, but the large joints are typically spared. Distal arthrogryposes are a heterogeneous group of disorders, many of which are associated with a specific gene defect in one of a number of genes that encode components of the contractile apparatus. Many distal arthrogryposes are transmitted as autosomal dominant disorders, but X-linked mutations are known.