Genetic polymorphisms of XPD and CDA and lung cancer risk.

To determine the susceptibility genes of lung cancer, we investigated the frequency distributions of the xeroderma pigmentosum complementary group D (XPD) and cytidine deaminase (CDA) genes in patients. A case-control study was conducted involving lung cancer patients and healthy controls. The genotypic distributions of XPD exon 10 G→A (Asp312Asn) and 23 T→G (Lys751Gln), and CDA 79 A→C (Lys27Gln) and 208 G→A (Ala70Thr), were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results demonstrated that the XPD Asp312Asn genotype distribution was G/G (82.52%) and A/G (17.48%) in the lung cancer patients, and G/G (82.52%), A/G (16.50%) and A/A (10.98%) in the controls. The genotypes of Lys751Gln were T/T (83.49%) and T/G (16.50%) in the lung cancer patients, and T/T (84.47%) and T/G (15.53%) in the controls. Mutations in the XPD single nucleotide polymorphism loci did not demonstrate a significant difference between the two groups (P>0.05). The risk of lung cancer in individuals with mutations at positions 312 and 751 increased 6.13-fold (P=0.047). The CDA Lys27Gln genotype distribution was A/A (78.65%), A/C (20.39%) and C/C (0.98%) in the lung cancer patients, and A/A (79.61%), A/C (19.42%) and C/C (0.98%) in the controls (P=0.985). The CDA Ala70Thr genotype distribution was G/G (98.06%) and A/G (1.94%) in the controls, while all the genotypes were wild-type in the lung cancer patients. The difference between the lung cancer patients and the controls was not statistically significant (P=0.155). There was also no significant difference in the frequency distribution of XPD or CDA between the different pathological types (P>0.05). Our findings demonstrate that the mutation of XPD codons 312 and 751 increases the risk of lung cancer. By contrast, polymorphisms of CDA appear to have little association with lung cancer.