Allele Frequencies of CYP2E1 Gene Polymorphisms in Iranian Populations

The only member of human cytochrome P450 E subfamily is CYP2E1 (Zhuge et al., 2003), located in the 10q24.3-qter region of chromosome 10. It contains 9 exons, 8 introns, and a typical TATA box and it spans 11,413 base pairs of genomic DNA (Umeno, 1988). CYP2E1 plays a key role in the metabolic activation of many low molecular weight carcinogens (e.g., benzene, N-nitrosamines, carbon tetrachloride chloroform and vinyl chloride) and producing reactive oxygen species (e.g., superoxide anion radical, hydrogen peroxide), which can affect target tissue and ultimately lead to carcinogenesis (Hou et al., 2007; Guo et al., 2010; Feng et al., 2012). CYP2E1 has several polymorphisms. Studies reported that its functional polymorphisms are associated with increased and decreased susceptibility to many cancer types, including esophageal cancer, lung cancer, nasopharyngeal carcinoma, and colorectal cancer (Cai et al., 2005; Sangrajrang et al., 2006). CYP2E1*5B (rs2031920) and CYP2E1*6 (rs6413432)