Dystrophin immunostaining and freeze-fracture studies of muscles of patients with early stage amyotrophic lateral sclerosis and Duchenne muscular dystrophy

Abstract

We used polyclonal antibodies against dystrophin for the immunohistochemical localization of this protein in human skeletal muscle. Dystrophin was localized in the sarcolemma of the myofibers in 8 infantile and 11 adult normal control muscles and in 10 early stage patient muscles with amyotrophic lateral sclerosis (ALS). The protein was absent or markedly decreased in 8 early stage patients with Duchenne muscular dystrophy (DMD). Moreover the densities of sarcolemmal plasma membrane assemblies, orthogonal arrays and their pits were estimated by freeze-fracture electron microscopy studies in the same number of muscle samples in each disease and control case. The group median densities of orthogonal arrays and their pits in the ALS group and adult control group were 4.8 with a midrange of 1.1–13.5 (25–75%) and 7.5 with a midrange of 2.3–12.9, respectively ( P > 0.1, Wilcoxon rank-sum test), whereas those of the DMD group and child control group were 0 with a midrange of 0–1.1 and 10.8 with a midrange of 5.4–16.7 respectively ( P < 0.01). The skeletal muscles of mdx mice and their controls were also investigated by the same techniques. In mdx mice, the absence or marked deficiency of dystrophin was also noted; however, the decrease of orthogonal arrays was not as severe as in DMD, which might relate to the milder clinical features in mdx mice as compared with those in DMD.