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An Allele-specific Gene Expression Assay to Test the Functional Basis of Genetic Associations
Published on: November 3, 2010
Evidence for population variation in TSC1 and TSC2 gene expression
Garilyn M Jentarra1, Stephen G Rice, Shannon Olfers
1Neurology Research Department, Barrow Neurological Institute, Phoenix, AZ 85013, USA.
BMC Medical Genetics
|February 25, 2011
Summary
Tuberous sclerosis complex (TSC) severity may be influenced by allele-specific mRNA expression differences in TSC1 and TSC2 genes. This study found such expression variations in healthy individuals, suggesting a role in TSC disease variability.
Area of Science:
- Genetics
- Molecular Biology
- Neurogenetics
Background:
- Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in TSC1 or TSC2 genes, leading to varied symptoms like epilepsy and intellectual disability.
- TSC presents with diverse phenotypes, even within families with identical mutations, suggesting factors beyond the primary genetic defect influence disease severity.
- Potential modifiers include somatic mutations, mosaicism, gene interactions, environmental factors, and crucially, differential mRNA expression from TSC alleles.
Purpose of the Study:
- To investigate whether allele-specific differences in mRNA expression (allelic expression imbalance - AEI) of TSC1 and TSC2 genes contribute to phenotypic variability in Tuberous Sclerosis Complex.
- To explore if common genetic variants influencing mRNA expression, detectable in non-affected individuals, correlate with disease severity in TSC.
Main Methods:
- Utilized a PCR/primer extension assay to quantify allele-specific expression of TSC1 and TSC2 mRNAs.
- Analyzed mRNA from leukocytes of normal volunteers, employing heterozygous single nucleotide polymorphisms (SNPs) as markers for AEI measurement.
Main Results:
- Demonstrated for the first time that TSC1 and TSC2 genes exhibit allele-specific differences in mRNA expression in blood leukocytes from normal individuals.
- These findings indicate that AEI is a naturally occurring phenomenon for TSC genes in the general population.
Conclusions:
- The observed allele-specific mRNA expression variations in TSC1 and TSC2 support the hypothesis that AEI contributes to the variable clinical severity observed in Tuberous Sclerosis Complex patients.
- This suggests that AEI could be a significant, yet previously unrecognized, factor in modulating TSC disease presentation and progression.
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