Congenital mirror movement disorder is a condition in which intentional movements of one side of the body are mirrored by involuntary movements of the other side. For example, when an affected individual makes a fist with the right hand, the left hand makes a similar movement. The mirror movements in this disorder primarily involve the upper limbs, especially the hands and fingers. This pattern of movements is present from infancy or early childhood and usually persists throughout life, without other associated signs and symptoms. Intelligence and lifespan are not affected.

Congenital mirror movement disorder can be caused by mutations in the DCC or RAD51 gene; mutations in these genes account for a total of about 35 percent of cases. Mutations in other genes that have not been identified likely account for other cases of this disorder.

Congenital mirror movement disorder is a very rare disorder. Its prevalence is thought to be less than 1 in 1 million. Researchers suggest that some mildly affected individuals may never be diagnosed.

In most cases, including those caused by mutations in the DCC or RAD51 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 most cases, an affected person has one parent with the altered gene. Some people who have the altered gene never develop the condition, a situation known as reduced penetrance.

Published Date: April 01, 2015Published By: National Institutes of Health