Emerin evaluation in Emery-Dreifuss muscular dystrophy patients

The diagnosis of X-linked Emery-Dreifuss muscular dystrophy (EDMD) is now normally confirmed by genetic analysis of the recently discovered STA gene which codes for the protein emerin. This is a ubiquitous protein which decorates the nuclear rim of many cell types. We evaluated by immunocytochemistry emerin expression in muscle and skin from 8 EDMD patients and in the skin from a EDMD carrier. Emerin was absent or partially expressed at the nuclei in muscle and skin from the patients and was expressed only in a few nuclei in the skin from the carrier. Immunoblot of peripheral blood cells from EDMD patients showed either absence of the emerin band, or altered size emerin, or a protein of normal molecular weight but slightly reduced quantity. The type and site of mutations in EDMD patients correlate with absence, or partial expression, of emerin. Immunocytochemical evaluation of emerin expression in skin biopsies is a sensitive and convenient tool for diagnosing the Xlinked EDMD and, in particular, for distinguishing it from the autosomal dominant form. This technique may be applied to suspected EDMD patients, especially sporadic cases or those with incomplete clinical phenotype, and also suspected carriers. Immunoblot of peripheral blood cells is also useful, however it may not unequivocally identify carriers and some patients.