Structural proteins of the opaque muscle fibers in Duchenne muscular dystrophy.

We studied the structural proteins of the "opaque fibers" (OFs) in muscle biopsies from 12 patients, aged 4 to 24 years, with Duchenne muscular dystrophy. The electrophoretic patterns of myofibrillar proteins indicated three groups of opaque fibers: the first (OF a) had an almost normal electrophoretogram, the second (OF b1) showed a clear decrease of 55,000 dalton protein (desmin), and the third (OF b2) exhibited a great reduction in alpha-actinin and desmin. The data suggest that some OFs are pathologic fibers in the degenerative process of Duchenne dystrophy.