Functional significance of dystrophin-positive fibers in Duchenne and Becker muscular dystrophy.

In this study, the ratios of dystrophin-positive (+), partially deficient (+/-), and deficient (-) fibers were investigated immunohistochemically in 28 Duchenne muscular dystrophy (DMD) and 4 Becker muscular dystrophy (BMD) patients using Dys I (midrod), Dys II (COOH-terminal), and Dys III (NH2-terminal) antibodies. In the biopsies of DMD patients, Dys II was negative in all cases; the mean ratio of Dys I (+) fibers was 0.05%, Dys I (+/-) 1.02%, Dys III (+) 0.27%, and Dys III (+/-) 0.75%. There was no correlation between these (+) or (+/-) fibers and the severity of clinical or laboratory findings. In BMD patients, it was shown that amino and carboxyl terminals of dystrophin could be affected in addition to the midportion.