RESEARCH COMMUNICATION Effects of Amino Acid Substitution Polymorphisms of two DNA Methyltransferases on Susceptibility to Sporadic Colorectal Cancer

Background and Aim: The present study was designed to consider whether amino acid substitution polymorphisms in O6-methylguanine-DNA methyltransferase (MGMT) and DNA methyl transferase 1 (DNMT1) genes may be associated with the genetic susceptibility to sporadic colorectal cancer. Patients and methods: 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 two groups. Results: The calculated odds ratios indicated no association between DNMT1 and colorectal cancer. However, there was a significant association between two polymorphisms in MGMT with sporadic colorectal cancer: Arg128Gln (OR, 5.53) and Gly160Arg (OR, 3.04). Conclusions: These findings could be indicative of factors contributing to high occurrence of Iranian colorectal cancer patients. Key words: MGMT- DNMT1- amino acid substitution polymorphisms- colorectal cancer- Ira