Muscular dystrophy, Emery-Dreifuss: A form of muscular dystrophy (MD) that begins in childhood or the teen years. It is a slowly progressing disorder that begins in the upper arms or upper legs. Contractures of the limbs are common, as are serious heart problems. Emery-Dreifuss MD is caused by mutation in the gene that encodes emerin on the X chromosome. Although only males have the muscle problems associated with Emery-Dreifuss MD, females may have the heart problems. Therefore, female relatives of males with this disorder should have regular heart checkups.