Risk Modulation of Oral Pre Cancer and Cancer with Polymorphisms in XPD and XPG Genes in North Indian Population

Abstract

Background: Environmental carcinogens cause DNA damages which if not repaired properly, may increase the<br />risk of cancer. The Xerodermapigmentosum group D (XPD) and group G (XPG) genes are essential genes for DNA<br />repair and alteration in DNA repair causes cancer. The present study aimed to evaluate the relationship between XPD<br />and XPG polymorphisms and risk of oral pre cancer and cancer. Methods: Present study genotyped 302 samples of<br />oral diseases and 300 controls for XPD (A/C) and XPG (G/C) polymorphisms with PCR-RFLP method. Results: Our<br />result showed that compared to AA genotype frequency of AC and CC genotype for XPD(A/C) polymorphism were<br />significantly lower among cases than in control and are associated with decreased risk of oral diseases (OR= 0.621<br />and 0.603 respectively). In contrast with reference to GG genotype the frequency of CC genotype of XPG (G/C) was<br />significantly higher in case than in control population (p value=0.004) and found to increase the risk of oral diseases<br />(OR= 2.077). Particularly C allele for XPD A/C polymorphism was found to be associated with decreased risk of Lichen<br />planus and increased risk of ( OR = 0.470 and 1.541 respectively) oral cancer. While C allele of XPG G/C polymorphism<br />significantly increased the risk of Oral Submucous Fibrosis and Leukoplakia (OR= 1.879 and 1.837 respectively) but<br />not of Lichen planus and oral cancer. In combined genotype analysis from the aforesaid polymorphisms presence of C<br />allele for XPD (A/C) polymorphisms were found to decrease the risk of oral diseases. However, the same C allele was<br />observed to increase the chance of having high stage disease (OR= 5.71) with nodal involvement (OR= 6.78) once the<br />cancer been initiated. Conclusion: This work shows association of XPD (A/C), XPG (G/C) polymorphisms with the<br />development of pre oral cancer as well as oral cancer and its clinical courses.