Histochemically demonstrable fibre abnormalities in normal skeletal muscle and in muscle from carriers of Duchenne muscular dystrophy.

Deltoid muscle was removed at motor point biopsy from 10 female relatives of patients with Duchenne muscular dystrophy and from seven others, with no evidence of neuromuscular disease. Transverse cryostat sections of the muscle from each case were stained for reduced diphosphopyridine nucleotide diaphorase and it was found that all contained varying numbers of degenerating type 1 fibres. The percentage of abnormal fibres in the type 1 fibre population was then calculated for each case and it was found that the muscles from the patients with dystrophic relatives contained considerably higher percentages of abnormal fibres, which also showed more severe degeneration, than did the muscles from the normal cases. There was no absolute correlation between serum creatine kinase levels and degree of pathological change, though patients with the most severe changes in their muscles had abnormally high serum creatine kinase levels. It is suggested that histochemical studies could be a useful addition to the present diagnostic tests for the carrier state in Duchenne muscular dystrophy.