Cytochemistry of cultured fibroblasts in myotonic muscular dystrophy

The cytoplasm of cultured skin fibroblasts derived from four unrelated and from three related patients with myotonic muscular dystrophy exhibits high amounts of metachromatic granular material and of alcianophilic material with Alcian blue containing 0.1 M MgCl2. Alcianophilia disappears when the staining solution contains 0.3 M MgCl2, i.e. is probably due only to carboxyl group of glycosaminoglycans.