PATHOLOGY OF MUSCULAR HYPOTONIA IN PRADER-WILLI SYNDROME LIGHT AND ELECTRON MICROSCOPIC STUDY

The clinical picture of the Prader-Willi syndrome (HHHO) is briefly reviewed. The first ultrastructural observations of muscle in this syndrome are described. They consist of: (1) subsarcolemmal aggregates of mitochondria; (2) abnormalities of the Z-line; and (3) myofilamentous disarray and loss. The etiology of the hypotonia, one of the most prominent features of HHHO syndrome, is discussed. The ultrastructural changes observed could be compatible with either myopathy or neuropathy, or could even result from muscular immobility and disuse. © 1969.