Glycogenin-1 deficiency and inactivated priming of glycogen synthesis.
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.
Moslemi
Ali-Reza
AR
Department of Pathology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
Lindberg
Christopher
C
Nilsson
Johanna
J
Tajsharghi
Homa
H
Andersson
Bert
B
Oldfors
Anders
A
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
D018389:Codon, Nonsense; D018076:DNA, Complementary; D006023:Glycoproteins; D012333:RNA, Messenger; C051887:glycogenin; D006003:Glycogen; D005964:Glucosyltransferases