Glu346Lys polymorphism in the methyl-CpG binding domain 4 gene and the risk of primary lung cancer.

BACKGROUND Methyl-CpG binding domain 4 (MBD4) protein functions as a DNA repair enzyme and minimizes mutations at 5-methylcytosine. Polymorphisms in the DNA repair gene MBD4 may be associated with differences in DNA repair capacity and thereby influence an individual's susceptibility to lung cancer. To test this hypothesis, we examined the potential association between the MBD4 Glu346Lys polymorphism and the risk of lung cancer in a Korean population. METHODS The MBD4 Glu346Lys genotypes were determined in 432 lung cancer patients and 432 healthy age- and gender-matched control subjects. RESULTS The distribution of the MBD4 Glu346Lys genotypes was not significantly different between the overall lung cancer cases and the controls. However, when the cases were categorized by tumor histology, the Lys346Lys genotype was associated with a significantly decreased risk of adenocarcinoma (AC) as compared with the Glu346Glu genotype [adjusted odds ratio (OR) = 0.50, 95% confidence interval (CI) = 0.26-0.97, P = 0.04]. On the stratification analysis, the protective effect of the Lys346Lys genotype against AC was statistically significant in older individuals and heavier smokers (adjusted OR = 0.08, 95% CI = 0.01-0.64, P = 0.02; and adjusted OR = 0.09, 95% CI = 0.01-0.72, P = 0.02, respectively). CONCLUSIONS Our findings suggest that the MBD4 Glu346Lys polymorphism could be used as a marker for genetic susceptibility to AC of the lung.