Influence of Smoking on MLH1 gene Polymorphism: Insights into Colorectal Cancer Incidence

Authors

• Ali Mohammed Al-Abedi, Higher Institute of Nanotechnology for Graduate Studies, Al-Furat Al-Awsat Technical University, IraqFollow
• Rand Muhammed Abdul-Hussein Al-Husseini, Department of biology, Faculty of Science, University of Kufa, Iraq

Abstract

Background: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. The MutL Homolog 1 (MLH1) gene plays a critical role in DNA mismatch repair (MMR). Evidence suggests cigarette smoking increases CRC risk, potentially interacting with genetic factors.

Materials and Methods: This case-control study involved 50 Iraqi CRC patients and 50 age- and gender-matched healthy controls. The PCR-RFLP technique was employed for genotyping the -93G/A (rs1800734) polymorphism. Statistical analysis included Chi-square, Fisher's Exact Test, and logistic regression adjusted for confounders. Hardy-Weinberg Equilibrium (HWE) was assessed in controls.

Results: The frequency of the rs1800734 variant was significantly higher in CRC patients. The A-allele was more prevalent in the CRC group (41%) than controls (14%) (OR=4.27, 95%CI=1.7-14.53, p=0.003). The AA genotype was identified in 6 patients (all non-smokers) and was absent in controls and smoking subgroups. Logistic regression confirmed smoking exposure as an independent risk factor.

Conclusion: The MLH1 promoter polymorphism -93G/A contributes to CRC susceptibility among Iraqi patients. Smoking remains a significant risk factor, potentially interacting with genetic predisposition. However, the absence of AA genotype in smokers suggests a complex gene-environment interaction requiring further investigation.

Recommended Citation

Al-Abedi, Ali Mohammed and Al-Husseini, Rand Muhammed Abdul-Hussein (2026) "Influence of Smoking on MLH1 gene Polymorphism: Insights into Colorectal Cancer Incidence," Al-Bahir: Vol. 9: Iss. 1, Article 5.
Available at: https://doi.org/10.55810/2313-0083.1136

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