title: Manifesting heterozygotes in McArdle's disease: clinical, morphological and biochemical studies in a family.
abstract: We report a family with McArdle's disease with several affected individuals in two generations. This unusual pedigree for an autosomal recessive disease is explained by the existence of manifesting heterozygotes in the maternal line. The presence of symptoms in heterozygotes seems to be due to a decrease in myophosphorylase activity below a critical threshold, ranging between 30% and 45% of normal mean value. The occurrence of several manifesting heterozygotes in the maternal line only can be explained by compound heterozygosity of a defective allele and a pseudodeficient allele for myophosphorylase, or by a genetic factor which regulates the phenotypic expression of the gene.
authors: Department of Neurology, Catholic University, Rome, Italy.
authors: G
authors: G
authors: Manfredi
authors: G
authors: G
authors: Silvestri
authors: S
authors: S
authors: Servidei
authors: E
authors: E
authors: Ricci
authors: M
authors: M
authors: Mirabella
authors: E
authors: E
authors: Bertini
authors: M
authors: M
authors: Papacci
authors: M
authors: M
authors: Rana
authors: P
authors: P
authors: Tonali
mesh_terms: D000293:Adolescent; D000328:Adult; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006012:Glycogen Storage Disease Type V / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006579:Heterozygote; D006801:Humans; D007558:Italy; D008297:Male; D009132:Muscles / Q000201:enzymology; D009135:Muscular Diseases / Q000503:physiopathology; D010146:Pain / Q000503:physiopathology; D010641:Phenotype; D010762:Phosphorylase a / Q000172:deficiency / Q000378:metabolism
chemical_list: D006003:Glycogen; D010762:Phosphorylase a