Association of the XRCC1 Arg194Trp and Arg399Gln polymorphisms with depression and hopelessness levels in individuals exposed to sour gas

Some parts of Masjid-i-Sulaiman (MIS; southwest of Iran) are polluted by natural sour gas. Previously it has been shown that among MIS citizens the incidence of suicide attempts and self-burning and the frequency of depression and hopelessness are remarkably high. In order to investigate the association of the XRCC1 genetic polymorphisms (at codons 194 and 399) with depression and hopelessness levels of participants exposed to sour gas, the present cross-sectional study was carried out on 206 healthy persons living in the contaminated areas of MIS. The genotypes of XRCC1 were determined using PCR based method. Depression and hopelessness scores were determined using Beck's depression inventory and Beck's hopelessness scale, respectively. The “Arg/Trp + Trp/Trp” genotypes of Arg194Trp polymorphism were positively correlated with hopelessness and depression levels. However there was no statistical association between the genotypes of Arg399Gln polymorphism and the hopelessness and depression levels. Our data indicated that the Trp194-Arg399 haplotype was significantly associated with the higher hopelessness (OR = 3.95, 95% CI = 1.34-11.5, P = 0.012) and depression levels (OR = 2.55, 95% CI = 1.15-5.66, P = 0.021). The Trp194 vs Arg194 allele (OR = 4.49, 95% CI = 1.33-15.1, P = 0.008) and the Trp194-Arg399 vs Arg194-Arg399 haplotype (OR = 4.66, 95% CI = 1.35-16.1, P = 0.015) significantly increased in “hopeless and depressed persons” compared with the “without hopelessness and depression” group. The impact of polymorphisms on the function of XRCC1 deserve more attention and also further studies are required to conclude clinical diagnosis of depressive disorders in polluted areas of MIS and study the adverse effects of H2S on brain function.