Single Nucleotide Polymorphism Analysis of the Nucleotide Excision Repair Genes XPC, XPA, and XPG in the Indian Population

Abstract

We have analyzed single nucleotide polymorphisms (SNPs) in the XPC, XPA, and XPG genes of the nucleotide excision repair (NER) pathway in the Indian population. In the XPC gene we observed nine polymorphisms in the coding region, four polymorphisms in the intronic region, and two polymorphisms in the 5' untranslated region (UTR). In the XPA gene we observed one frequent SNP (allele frequency 0.48) within the 5' UTR at the 1665 position in a large proportion of the sample. In addition, we observed three novel heterozygous polymorphisms (a C to A transversion at position 1523 and a G to A transition at positions 1418 and 1458, with an allele frequency of 0.004) within the promoter region. In silico PCR analysis demonstrated that all three novel polymorphisms lie within a putative CpG island and that the variation at position 1418 falls within the potential GATA1/2/3 transcription factor(s) binding site and also within the negative control element. We performed a gel retardation assay with HeLa cell nuclear extract with an oligonucleotide encompassing this region. One of the alleles found at position 1458 of the XPA gene showed a significant change in protein-DNA interaction. In the XPG gene we found five polymorphisms in the coding region and one each in the 5' UTR of exon 1 and in intron 13.