title: Clinical and molecular characterization of McArdle's disease in Brazilian patients.
abstract: McArdle's disease, a glycogen storage disease type V, is caused by a deficiency of the enzyme myophosphorylase, encoded by the PYGM gene. Worldwide distribution of mutations has revealed interesting data about the prevalence of mutations and population migrations. Currently, more than 100 mutations in the PYGM gene have been described, with some recurrent mutations in the different populations. However, no molecular studies of McArdle's disease were reported in Brazilian patients. Here, we describe the clinical phenotype and genotype of 10 patients from 8 unrelated Brazilian families. Among the 10 patients (3 females, 7 males), eight presented with the typical phenotype, with exercise intolerance, cramps, and myalgia; one patient showed permanent muscle weakness; and one patient showed a mild phenotype. Molecular analysis identified 5 different mutations in the 8 families, both in homozygosis or compound heterozygosis state. Four of them had already been described (p.R50X, p.T692kfs30, p.K609K, and p.G455R), and one, pI513V, is a novel heterozygous mutation. The common nonsense p.R50X mutation was found in 6 of the 8 families, being therefore the commonest mutation in the Brazilian population as well. Other mutations previously reported in European patients were also found in the patients in this study, which was expected considering the European ancestry of the Brazilian population.
authors: Department of Pediatrics, Pediatric Neurology Service, Medical School, Universidade Federal de Minas Gerais, Rua Santa Catarina, 1042 apt: 201, Belo Horizonte, MG, Brazil. gurgelju@yahoo.com.br
authors: Juliana
authors: J
authors: Gurgel-Giannetti
authors: Gisela
authors: G
authors: Nogales-Gadea
authors: Hélio
authors: H
authors: van der Linden
authors: Túlio Marcus Ribeiro
authors: TM
authors: Bellard
authors: Geraldo
authors: G
authors: Brasileiro Filho
authors: Alexandre Varella
authors: AV
authors: Giannetti
authors: Eralda Luiza
authors: EL
authors: de Castro Concentino
authors: Mariz
authors: M
authors: Vainzof
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001706:Biopsy; D001938:Brazil / Q000453:epidemiology; D018389:Codon, Nonsense; D004576:Electromyography; D005060:Europe / Q000208:ethnology; D017079:Exercise Tolerance; D005260:Female; D005838:Genotype; D024982:Glycogen Phosphorylase, Muscle Form / Q000737:chemistry / Q000172:deficiency / Q000235:genetics*; D006012:Glycogen Storage Disease Type V / Q000208:ethnology / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009154:Mutation; D020125:Mutation, Missense; D009212:Myoglobinuria / Q000235:genetics; D010641:Phenotype; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D018389:Codon, Nonsense; D024982:Glycogen Phosphorylase, Muscle Form
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