Analysis of human glutathione S-transferase alpha 1 (hGSTA1) gene promoter polymorphism using denaturing high...

The GST enzyme, encoded by hGSTA1 gene, catalyses the GSH dependant detoxification of a variety of carcinogenic metabolites and alkylating chemotherapeutic agents. Two genetic variants of hGSTA1, namely hGSTA1*A and hGSTA1*B, are characterized by three linked SNPs, of which -52 G>A variation being solely responsible for the differential promoter activity of hGSTA1. Individuals homozygous for hGSTA1*B have low hepatic expression of hGSTA1. Given the time and labor consuming PCR-RFLP method and the direct prediction of -52 G>A variation, we opted to establish a high throughput DHPLC procedure for the characterization of hGSTA1 variants.

117 DNA samples from South India were included in the study. Control samples were generated for DHPLC using conventional PCR-RFLP technique. Heteroduplexes were produced by in vitro mixing of control DNA samples (hGSTA1*A) to all the samples which are subsequently subjected to DHPLC analysis. The samples were analyzed for the presence of heteroduplexes from the chromatographic profiles.

From the total of 117 samples, 43.5% are homozygous for hGSTA1*A allele, 13% are homozygous for hGSTA1*B allele and 43.5% are hGSTA1*A/B heterozygotes. This is, to our knowledge, the first report on the use of DHPLC for the evaluation of hGSTA1 gene promoter polymorphism.