Unusual type of neural muscular atrophy with a possible X-chromosomal inheritance pattern

In a large family five affected males belonging to four different kinships exhibited a muscle wasting of varying degree and with a predominantly proximal distribution. The index case had a facio-scapulo-humeral and peroneal muscular atrophy, whereas one of his cousins suffered a more generalized involvement starting in infancy and similar to Werdnig-Hoffman disease. The other affected family members had only slight changes. The index case and his affected brother had a positive Babinski sign. In enzyme histochemical preparations, specimens from the index case showed small group atrophy of type 2 fibers along with pseudomyopathic changes (whorled and coiled fibers, splitting) of type 1 fibers. Similar findings were observed in his cousin. Ultrastructural investigation gave no further information. Since all patients were males and the offspring of unaffected sisters, an X-chromosomal mode of transmission is proposed for this illness.