Association of GSTM1 and GSTT1 Gene Deletions with Susceptibility to DNA Damage in the Pesticide-Exposed Workers of Punjab

The main aim of this study was to evaluate genotoxic effects of pesticides in association with glutathione S-transferase (GST) polymorphism. To achieve this aim, DNA damage and the genotypes of the GSTM1 and GSTT1 genes were studied from blood lymphocytes of pesticide-exposed and unexposed (control) agricultural workers of the Punjab region of northwestern India. The blood samples were collected from 40 exposed and 27 unexposed subjects from the Kakrala and Sanour villages of Patiala district. DNA damage was evaluated by using an alkaline comet assay. The analysis of the comets was done through visual scoring and image analysis software (Tritek's CometScore (TM)). Damage Index (DI), Damage Frequency (DF) (calculated by visual scoring method), and % DNA in tail (measured by image analysis software) were considered for assessing DNA damage. The DNA extraction from blood cells was done using proteinase K and the phenol-chloroform method, and genotyping of GSTM1 and GSTT1 was done using multiplex PCR. It was found that all the pesticide-exposed subjects showed higher DI, DF, and % DNA in tail in comparison to the controls. The statistical comparison of DNA damage between the exposed group and unexposed group revealed highly significant differences (p < 0.05; Mann-Whitney U-test). In addition, the GSTT1 gene deletion and simultaneous deletions of GSTM1 and GSTT1 genes in increasing DNA damage were observed in the exposed group.