title: Muscle phosphofructokinase deficiency: abnormal polysaccharide in a case of late-onset myopathy.
abstract: A 61-year-old woman with muscle phosphofructokinase (PFK) deficiency had mild limb weakness all her life but no cramps or myoglobinuria. For 5 years the limb weakness progressed. In muscle, PFK activity was 1% of normal and glycogen concentration was elevated (2.13%). By light microscopy, a minor component of the accumulated glycogen appeared as PAS-positive, diastase-resistant inclusions in 10% of muscle fibers. The inclusions had a filamentous fine structure that resembled the abnormal long-chain glycogen of brancher enzyme deficiency. Iodine absorption spectra of both the inclusions and a diastase-resistant fraction of isolated glycogen resembled amylopectin. The abnormal polysaccharide in PFK deficiency may be related to greatly elevated concentration of muscle glucose-6-phosphate, an activator of the chain-elongating enzyme glycogen synthase.
mesh_terms: D002648:Child; D005260:Female; D006008:Glycogen Storage Disease / Q000378:metabolism*; D006014:Glycogen Storage Disease Type VII / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D006651:Histocytochemistry; D006801:Humans; D008875:Middle Aged; D009132:Muscles / Q000378:metabolism* / Q000648:ultrastructure; D009135:Muscular Diseases / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D011134:Polysaccharides / Q000378:metabolism*
chemical_list: D011134:Polysaccharides