Emery-Dreifuss muscular dystrophy and other related disorders.

There are some 30 or so different forms of muscular dystrophy which are conveniently classified according to the mode of inheritance. Emery-Dreifuss X-linked muscular dystrophy is characterized by the triad of: (1) early contractures of the elbows, Achilles tendons and postcervical muscles; (2) slowly progressive muscle wasting and weakness with a humero-peroneal distribution in the early stages; and (3) a cardiomyopathy usually presenting as heart-block. The insertion of a cardiac pace-maker can be life saving and therefore the recognition of the condition is essential. The responsible gene has been localized to Xq28. The autosomal recessive dystrophies are classified into congenital forms (the Fukuyama type is particularly common in Japan); a childhood form (similar to Duchenne) which occurs frequently in certain inbred communities; and adult onset limb girdle dystrophy. The autosomal dominant dystrophies are classified on the distribution of predominant muscle weakness into facioscapulohumeral, scapuloperoneal (with or without early contractures and cardiomyopathy), proximal, distal and ocular forms. The basic biochemical defects and the localizations of the responsible genes are as yet unknown in any of the autosomal recessive or autosomal dominant dystrophies.