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The intracellular localization of myoglobin(Mb) mRNA in the skeletal muscles of normal subjects and patients with Duchenne muscular dystrophy(DMD) or amyotrophic lateral sclerosis(ALS) was examined by in situ hybridization using a biotin-labeled cDNA probe. In cross sections of normal muscles, Mb mRNA signals were demonstrated to be diffusely distributed as granular reaction products throughout the sarcoplasm, and in longitudinal sections the products were observed preferentially on the A-band. In DMD or ALS muscles, the distribution of granular mRNA signals showed some similarities with that in normal muscles, although degenerated fibers revealed a heterogenous distribution of the signals. In DMD muscles, the optical density(OD) of stained signal was higher in non-atrophic fibers and lower in atrophic fibers than in normal muscles. In ALS muscles, the OD was lower than in normal muscles. These results suggest that Mb mRNA is distributed preferentially on the A-band of the muscle fibers, and that in diseased muscle fibers Mb synthesis is affected by pathological changes.

We investigated the expression of alpha-sarcoglycan, beta-sarcoglycan, gamma-sarcoglycan, and delta-sarcoglycan immunohistochemically in three patients with mutations of the alpha-sarcoglycan gene and a patient with a mutation of the gamma-sarcoglycan gene. Although each of the four sarcoglycans were decreased on the muscle membranes of all the patients, different expression patterns for each were seen among the patients. In patients with mutations of the alpha-sarcoglycan gene, beta-, gamma- and delta-sarcoglycans were relatively preserved as compared to greatly reduced alpha-sarcoglycan. However, the patient with a mutation of the gamma-sarcoglycan gene showed marked reduction of gamma-sarcoglycan as compared to partially preserved alpha- and beta-sarcoglycans, and well-preserved delta-sarcoglycan. These results suggest that each sarcoglycan component in sarcoglycanopathy does not decrease in the same manner, and that mutations of the sarcoglycan gene can be predicted, at least in part, by means of sensitive immunohistochemistry for each sarcoglycan.