Congenital myopathy with "reducing bodies" in muscle fibres.

A muscle biopsy of a boy of 14 years presenting clinically a benign congenital myopathy showed granular intrasarcoplasmic bodies exhibiting reducing activity. The resemble the bodies described by Brooke and Neville in muscle of two children with severe congenital myopathy which they referred to as "reducing body myopathy". If the reducing bodies are the characteristic morphological feature peculiar to this newly recognized congenital myopathy, the case reported here would be therefore a benign form of reducing body myopathy. The origin and nature of the granular material forming the bodies is doubtful. The close relationship between this material and the myofilaments may suggest that the granules arise from some myofibrillary component.