Impact of Tobacco on Glutathione S Transferase Gene Loci of Indian Ethnics


Background: Tobacco contains agents which generate various potent DNA adducts that can cause genemutations. Production of DNA adducts may be neutralized by glutathione S transferase (GST) along with otherphase I and phase II enzyme systems. The existence of null type of GST among the population increases thesusceptibility to various disorders and diseases. The present study focuses on the impact of high tobacco usage andpossible null type mutation in GST loci.
Methods: Genotypes of GST were detected by multiplex polymerase chainreaction in unrelated 504 volunteers of high tobacco using natives of Gujarat. Allelic frequencies were calculatedusing Statistical Package for Social Studies-16 software. Hardy Weinberg Equilibrium (HWE) was calculatedusing Chi square test. Two sided Fisher’s significance test was used to compare allelic frequencies of differentpopulations.
Results: The frequency of homozygous null genotype of GSTM1 and GSTT1 were 20% (95% CI16.7-23.9) and 35.5% (95% CI 31.4-39.9) respectively. The GSTM1 and GSTT1 null allele frequency distributionin the Gujarat population was significantly deviating from HWE. GSTT1 null frequency of Gujaratians wassignificantly higher and different to all reported low tobacco using Indian ethnics, while GSTM1 was not differingsignificantly.
Conclusion: Tobacco usage significantly influences the rate of mutation and frequency of GSTT1and M1 null types among the habituates. The rate of mutation in GSTT1 loci was an undeviating response tothe dose of tobacco usage among the population. This mutational impact of tobacco on GSTT1 postulates thepossible gene - environment interaction and selection of null genotype among the subjects to prone them undersusceptible status for various cancers and even worst to cure the population with GSTT1 dependent drugs.