Related Experiment Videos
Rare McArdle disease locus polymorphic site on 11q13 contains CpG sequence
R V Lebo1, L A Anderson, S DiMauro
1Department of Obstetrics, Gynecology, University of California, San Francisco 94143-0720.
Abstract:
When probes throughout the McArdle disease (myophosphorylase) gene region were used to search for DNA polymorphisms, only an MspI polymorphism was found in 94 enzyme-probe combinations. Along with an insertion/deletion polymorphism more 3' to the gene locus, these polymorphisms will be informative in 75% of at-risk patients. These results contrast strikingly to the six polymorphic sites detected in 15 enzyme-probe combinations in the homologous Her's disease (liver phosphorylase) gene region. This single MspI polymorphic site includes a CpG sequence of known increased mutability suggesting that DNA regions with rare polymorphisms will have most polymorphic sites at sequences with enhanced mutability. Fluorescence in situ hybridization sublocalized this gene to proximal band 11q13, establishing a point of cross-reference between the physical and genetic maps.
Insights
Researchers identified limited DNA polymorphisms in the McArdle disease gene region. These findings aid in genetic testing for patients at risk of this muscle disorder.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- McArdle disease, caused by myophosphorylase deficiency, requires genetic analysis for diagnosis and risk assessment.
- Identifying DNA polymorphisms within the myophosphorylase gene is crucial for developing informative genetic markers.
Purpose of the Study:
- To identify and characterize DNA polymorphisms in the McArdle disease (myophosphorylase) gene region.
- To compare polymorphism frequency with the homologous liver phosphorylase gene region.
Main Methods:
- Screening of the myophosphorylase gene region using DNA probes and enzyme digestion (MspI).
- Detection of insertion/deletion polymorphisms.
- Fluorescence in situ hybridization (FISH) for gene localization.
Main Results:
- Only one MspI polymorphism was identified in the McArdle disease gene region after extensive screening.
- An additional insertion/deletion polymorphism was found 3' to the gene locus.
- These polymorphisms are informative in 75% of at-risk patients.
- In contrast, six polymorphic sites were found in the homologous liver phosphorylase gene region.
- The identified MspI site contains a CpG sequence, suggesting increased mutability in regions with rare polymorphisms.
- The myophosphorylase gene was localized to chromosome 11q13 via FISH.
Conclusions:
- The McArdle disease gene region exhibits a low frequency of detectable DNA polymorphisms.
- The identified polymorphisms provide valuable tools for genetic counseling and carrier testing in McArdle disease.
- The study highlights a potential correlation between CpG sequences and polymorphism occurrence.
- Gene localization refines the physical and genetic mapping of the myophosphorylase gene.