REDUCING BODY MYOPATHY AND DESMIN STORAGE IN SKELETAL-MUSCLE - MORPHOLOGICAL AND BIOCHEMICAL FINDINGS

We describe clinical, morphological and biochemical findings of a pati ent with reducing body myopathy (RBM). This 15-year-old patient was af fected by severe limb-girdle progressive myopathy with asymmetric dist ribution. Muscle biopsy showed many fibers with cytoplasmic polymorphi c masses, which stained dark purple with modified Gomori's trichrome, associated with proliferation of cytoplasmic bodies. Cytoplasmic polym orphic masses showed marked reducing activity with menadione-nitro blu e tetrazolium reaction. Ultrastructurally, there was great amount of h ighly electron-dense tubular-filamentous structures of 16-17 nm in dia meter. Immunohistochemistry showed that many fibers were positive for desmin. Sodium dodecyl sulfate-electrophoresis disclosed an increase i n two bands of approximately 53 and 70 kDa, and Western blot demonstra ted that the 53-kDa band was desmin. It was not possible to characteri ze the 70-kDa protein further.