Amino acid substitution polymorphisms of two DNA methyltransferases and susceptibility to sporadic colorectal cancer

To evaluate the association of DNMT1 and MGMT amino acid substitution polymorphisms and colorectal cancer in Iranian population. The MGMT and DNMT1 are two important methyltransferase enzymes. Amino acid substitution polymorphisms in MGMT and DNMT1 genes may be associated with the genetic susceptibility to sporadic colorectal cancer.Patients and We assessed eight non-synonymous polymorphisms of these two genes by PCR/Pyrosequencing. Our population consisted of 208 individuals with sporadic colorectal cancer and 213 controls. Allele frequencies and genotypes were compared between the cases and controls. Odds ratios were calculated and there was no association between DNMT1 and colorectal cancer. However, there was a significant association between two polymorphisms with sporadic colorectal cancer; Arg128Gln (OR 5.53, 95%CI 2.58-7.16) and Gly160Arg (OR 3.04, 95%CI=1.48-6.31) of MGMT gene. This finding could be an accurate indicator of high occurrence of colorectal cancer in Iranian patients.