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December 1974

Muscle in Lafora Disease

Arch Neurol. 1974;31(6):396-406. doi:10.1001/archneur.1974.00490420062007

Ultrastructural studies of muscle from a patient with Lafora disease showed sheets of glycogen particles and fine granular-filamentous material between myofibrils. These structures were frequently intermingled and stained intensely with silver proteinate, a specific stain for polysaccharides. Methods for isolation of glycogen yielded excessive hexose-releasing material. In chromatographic analysis of a hydrolysate of this material, glucose was the only component sugar. Compared with action on normal muscle glycogen, phosphorylase was ineffective, β-amylase 50% less effective, but α-amylase normally effective in degrading the Lafora polyglucosan. Incubation of muscle homogenate or isolated polyglucosan with a mixture of glucosidases capable of completely degrading normal glycogen (Diazyme) resulted in only 30% digestion of the Lafora polyglucosan. The metabolic error causing the accumulation of anomalous polysaccharide in this generalized storage disease remainsobscure.