title: Glycogenin-1 deficiency and inactivated priming of glycogen synthesis.
abstract: Glycogen, which serves as a major energy reserve in cells, is a large, branched polymer of glucose molecules. We describe a patient who had muscle weakness, associated with the depletion of glycogen in skeletal muscle, and cardiac arrhythmia, associated with the accumulation of abnormal storage material in the heart. The skeletal muscle showed a marked predominance of slow-twitch, oxidative muscle fibers and mitochondrial proliferation. Western blotting showed the presence of unglucosylated glycogenin-1 in the muscle and heart. Sequencing of the glycogenin-1 gene, GYG1, revealed a nonsense mutation in one allele and a missense mutation, Thr83Met, in the other. The missense mutation resulted in inactivation of the autoglucosylation of glycogenin-1 that is necessary for the priming of glycogen synthesis in muscle.
authors.affiliation: Department of Pathology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Ali-Reza
authors.initials: AR
authors.lastname: Moslemi
authors.forename: Christopher
authors.initials: C
authors.lastname: Lindberg
authors.forename: Johanna
authors.initials: J
authors.lastname: Nilsson
authors.forename: Homa
authors.initials: H
authors.lastname: Tajsharghi
authors.forename: Bert
authors.initials: B
authors.lastname: Andersson
authors.forename: Anders
authors.initials: A
authors.lastname: Oldfors
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology; D018389:Codon, Nonsense; D018076:DNA, Complementary / Q000032:analysis; D004244:Dizziness / Q000209:etiology; D005260:Female; D005964:Glucosyltransferases / Q000172:deficiency* / Q000235:genetics*; D006003:Glycogen / Q000096:biosynthesis*; D006023:Glycoproteins / Q000172:deficiency* / Q000235:genetics*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000473:pathology; D020125:Mutation, Missense; D010375:Pedigree; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA
chemical_list: D018389:Codon, Nonsense; D018076:DNA, Complementary; D006023:Glycoproteins; D012333:RNA, Messenger; C051887:glycogenin; D006003:Glycogen; D005964:Glucosyltransferases