Background: The -93G > A (rs1800734) polymorphism within the core promoter region of MLH1 gene is associated with MLH1 CpG island hypermethylation. This polymorphism has recently been proposed as a low penetrance variant for colorectal cancer. Many published studies have evaluated the association between the MLH1 -93G > A polymorphism and colorectal cancer risk. However, the results remain conflicting rather than conclusive. The aim of this study was to assess the association between the MLH1 -93G > A polymorphism and the risk of colorectal cancer in patients with colorectal cancer in the lower northeastern region of Thailand.
Methods: One hundred fifty one samples from colorectal cancer patients and 100 samples from healthy control group were analyzed. Genomic DNA was extracted from white blood cell of all samples. The real-time polymerase chain reaction (qPCR) was used to demonstrate genetic polymorphism of MLH1 rs1800734.
Results: This study demonstrated that the frequency of MLH1 rs1800734 in patients with colorectal cancer was higher than healthy control group. The MLH1 rs1800734 polymorphism variant AA was associated with an increased risk of colorectal cancer (p < 0.05). The MLH1 polymorphism variant AA carriers presented 1.36-folds high risk of colorectal cancer and the alcohol consumption was linked to their likelihood of developing colorectal cancer and their tumor's grade.
Conclusion: This study showed that MLH1 rs1800734 genotype AA was associated with colorectal cancer risk in the lower northeastern region of Thailand.
Keywords: MLH1 rs1800734; Thailand; colorectal cancer risk.