Definition of Congenital mirror movement disorder

Congenital mirror movement (CMM) disorder: a rare genetic disorder in which intentional movements made in one-half of the body are copied, or mirrored, by the other side of the body involuntarily. This abnormal movement begins in infancy or early childhood and can vary in severity among affected people. The condition occurs in less than 1 out of every 1 million people. The movements that are mirrored primarily involve the arms and hands. This can cause those affected to have problems with activities that require different movements of each hand. This is typically the only symptom, and intelligence or lifespan are not affected. Mutations in specific genes have been identified in about 35% of cases. The condition usually is inherited in an autosomal dominant manner, meaning only one parent must be affected to pass the condition to their offspring. Also known as bimanual synergia, mirror hand syndrome, and bimanual synkinesis.