Emery-Dreifuss muscular dystrophy (EDMD) was delineated as a separate form of
muscular dystrophy nearly 40 years ago, based on the distinctive clinical features of early
contractures and humero-peroneal weakness, and
cardiac conduction defects. The gene, STA at Xq28, for the commoner X-linked EDMD encodes a 34 kD nuclear membrane
protein designated '
emerin', and in almost all cases on immunostaining is absent in muscle, skin fibroblasts, leucocytes and even exfoliative buccal cells, and a mosaic pattern in female carriers. The gene, LMNA at 1q21, for the
autosomal dominant Emery-Dreifuss muscular dystrophy encodes other nuclear membrane
proteins,
lamins A/C. The diagnosis (at present) depends on mutation analysis rather than
protein immunohistochemistry. It is still not at
all clear how defects in these nuclear membrane
proteins are related to the phenotype, even less clear that LMNA mutations can also be associated with
familial dilated cardiomyopathy with no weakness, and even
familial partial lipodystrophy with
diabetes mellitus and
coronary heart disease! What began as clinical studies in a relatively rare form of dystrophy has progressed to detailed research into the functions of nuclear membrane
proteins particularly in regard to various forms of
heart disease.