Emery-Dreifuss muscular dystrophy: disease spectrum and differential diagnosis

We report six patients with Emery-Dreifuss muscular dystrophy (EDMD) and four patients including one female with EDMD phenotype (EDMDP). This series includes one sporadic case who had previously been reported in this journal under the diagnosis of "rigid spine syndrome" in 1977. Time of observation ranged from three to ten years. Detailed cardiological assessment was performed in all patients, skeletal muscle biopsies were obtained from 9 out of 10 and cardiac muscle biopsies from 2 out of 10 patients. One patient showed evidence of cardiomyopathy in the absence of clinically apparent neuromuscular disease and one sibling of another EDMD patient reportedly had a similar combination of symptoms which, to our knowledge, has not yet been reported. Cardiac involvement was found to consist of four independent, albeit often combined features: 1) impairment of impulse generating cells; 2) conduction defects with atrial preponderance; 3) increased atrial and ventricular heterotopia; and 4) functional impairment of ventricular myocardium. Ventricular involvement as apparent from ventricular heterotopia, abnormal enddiastolic diameter, decrease of contractility and/or morphological evidence of ventricular myocardial disease was found in 7 out of 10 patients and confirmed by myocardial histopathology in two EDMD patients. In one myocardial biopsy extensive accumulations of intermediate filaments were observed, a rare finding, which has not been linked to EDMD before. Skeletal muscle biopsies showed evidence of myopathy throughout but several equivocal features such as fibre type grouping in EDMD and fibre type disproportion in EDMDP were also observed. The variability of clinical manifestation of both cardiac and neuromuscular disease encompassed a broader spectrum than apparent from the literature. The consequences for the inherent differential diagnosis are discussed.