FAMILIAL CONGENITAL MIRROR MOVEMENTS: REPORT OF A LARGE 4-GENERATION FAMILY

Abstract

Mirror movements (MM) are synkinesias occurring in the opposite side during the intentional use of a limb. They are occasionally present in children, but persistence after age 10 is abnormal.1,2 We have found a large 4-generation family with congenital mirror movements not associated with other neurologic abnormalities. ### Methods. Nineteen members (11 affected and 8 unaffected) of a 4-generation family with individuals affected with congenital MM were interviewed in a systematic questionnaire that queried perinatal history, development, presence of learning disabilities, and other medical history. Information regarding the onset, distribution, suppressibility, and functional and social impact of MM was obtained. A videotaped examination was performed, and subjects underwent diadochokinesimeter measurement of rapid alternating pronation-supination movements at 2 different velocities. The diadochokinesimeter consisted of 2 hand-held plastic spheres connected to optical encoders, which recorded amplitude and velocity of movement in each hand.3 This project was approved by the Institutional Review Board of the Centre Hospitalier de l’Universite de Montreal. ### Results. This French Canadian family originates from the Lanaudiere region of Quebec. There is no known consanguinity. Transmission is autosomal dominant with high but incomplete penetrance. Penetrance is higher in males (figure). Figure Pedigree of the family with congenital mirror movements illustrating autosomal dominant inheritance with incomplete penetrance The index case first sought neurologic attention for episodes of fatigue, and MM were incidentally noted on examination. They had been present since childhood, and had never …