Gene Frequencies of the Human GSTT1 (Null Allele) and GSTP1 (Ile105Val) Polymorphisms among South Indian Populations

Background: Glutathione S-transferases (GSTs) are members of the phase II biotransformation enzymes that play a key role in cellular detoxification of chemical carcinogens and xenobiotics. Variations at GST genes have been reported in different human populations, and some association studies have reported increased risk for cancers and other disease end points. The present study was conducted to investigate the allele frequency variations in south Indian populations. Methods: GSTT1 null allele and GSTP1 Ile105Val polymorphisms were genotyped in two hundred and twelve subjects (aged 34 to 60 years old) belong to six populations using PCR and PCR-RFLP techniques respectively. Results: Both GSTT1 ins-del and GSTP1 Ile105Val are polymorphic in all populations. GSTP1 Ile105Val followed the Hardy-Weinberg equilibrium. The GSTT1 null allele frequencies ranged from 11.6% to 22.2% and GSTP1 Ile105Val “Val” allele frequency ranged from 20.0% to 38.2% in the study populations. HapMap data showed the highest frequency of Val105 allele in African populations followed by European populations. East Asian populations showed the lowest frequency of Val105 allele. Conclusion: The variations observed in allelic distribution of GST genes may presumably be due to the selective pressure exerted on populations of that region. In conclusion, the present study reports the frequency of GSTT1 null allele and GSTP1 Ile105Val polymorphisms in Indian populations which provides foundation for potential epidemiological and clinical studies.