Document Detail


High frequency of missense mutations in glycogen storage disease type VI.
MedLine Citation:
PMID:  17705025     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Deficiency of liver glycogen phosphorylase in glycogen storage disease (GSD) type VI results in a reduced ability to mobilize glucose from glycogen. Six mutations of the PYGL gene, which encodes the liver isoform of the enzyme, have been identified in the literature. We have characterized eight patients from seven families with GSD type VI and identified 11 novel PYGL gene defects. The majority of the mutations were missense, resulting in the substitution of highly conserved residues. These could be grouped into those that were predicted to affect substrate binding (p.V456M, p.E673K, p.S675L, p.S675T), pyridoxal phosphate binding (p.R491C, p.K681T), or activation of glycogen phosphorylase (p.Q13P) or that had an unknown effect (p.N632I and p.D634H). Two mutations were predicted to result in null alleles, p.R399X and [c.1964_1969inv6;c.1969+1_+4delGTAC]. Only 7 of the 23 (30%) reported PYGL alleles carry nonsense, splice site or frameshift mutations compared to 68-80% of affected alleles of the highly homologous muscle glycogen phosphorylase gene, PYGM, that underlie McArdle disease. There was heterogeneity in the clinical symptoms observed in affected individuals. These varied from hepatomegaly and subclinical hypoglycaemia, to severe hepatomegaly with recurrent severe hypoglycaemia and postprandial lactic acidosis. We conclude that deficiency of liver glycogen phosphorylase is predominantly the result of missense mutations affecting enzyme activity. There are no common mutations and the severity of clinical symptoms varies significantly.
Authors:
N J Beauchamp; J Taybert; M P Champion; V Layet; P Heinz-Erian; A Dalton; M S Tanner; E Pronicka; M J Sharrard
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-08-21
Journal Detail:
Title:  Journal of inherited metabolic disease     Volume:  30     ISSN:  1573-2665     ISO Abbreviation:  J. Inherit. Metab. Dis.     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-10-10     Completed Date:  2007-10-25     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7910918     Medline TA:  J Inherit Metab Dis     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  722-34     Citation Subset:  IM    
Affiliation:
Academic Unit of Child Health, University of Sheffield, Stephenson Wing, Sheffield Children's NHS Trust, Western Bank, Sheffield, S10 2TH, UK. n.j.beauchamp@sheffield.ac.uk
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Animals
Blood Glucose / metabolism
Child, Preschool
DNA Mutational Analysis
Exons
Female
Genetic Predisposition to Disease
Genotype
Glycogen Phosphorylase, Liver Form / chemistry,  deficiency,  genetics*
Glycogen Storage Disease Type IV / enzymology,  genetics*
Humans
Infant
Introns
Lactic Acid / blood
Liver / enzymology*
Male
Models, Molecular
Molecular Sequence Data
Mutation, Missense*
Pedigree
Phenotype
Protein Conformation
Sequence Alignment
Sequence Homology, Amino Acid
Severity of Illness Index
Chemical
Reg. No./Substance:
0/Blood Glucose; 50-21-5/Lactic Acid; EC 2.4.1.-/Glycogen Phosphorylase, Liver Form

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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