Unusual expression of emerin in a patient with X-linked Emery-Dreifuss muscular dystrophy

We report on a patient with the typical clinical findings of Emery-Dreifuss muscular dystrophy due to a mutation in the emerin gene that should have produced a higher molecular weight protein. Immunohistochemical analysis showed emerin localized only in the cytoplasm of muscle fibres and lymphoblastoid cells. The emerin molecule contained the nucleoplasmic domain and the transmembrane domain responsible for nuclear membrane targeting, so its incorrect localization and lack of function could be due to abnormal folding resulting in rapid degradation or inability to bind other nuclear proteins.