XPD common variants and their association with melanoma and breast cancer risk.

There are suggestions in the literature that common variants in the XPD gene may be associated with an altered risk of melanoma and breast cancer. To establish if the XPD common variants Asp312Asn and Lys751Gln are associated with an increased melanoma or breast cancer risk we performed an association study based on genotyping 426 unselected patients with malignant melanoma (MM) and 1830 consecutive breast cancer cases and compared the results to 1262 geographically matched newborns, 621 adults from the region of Szczecin (unselected for age and cancer family history), 421 healthy adults age- and sex-matched with the melanoma cases and 511 healthy controls matched with the breast cancer patients from the region of Szczecin. Additionally we examined the prevalence of three additional XPD variants, Gly156Gly, Leu485Pro and Arg112His amongst the 421 unselected melanoma patients. All of the variants when evaluated singularly were found not to be associated either with melanoma or breast cancer risk in younger or older patients. A modest association was observed with breast cancer risk when the Lys751Gln_CC/Asp312Asn_AA genotype (OR=1.5, p<0.05) segregated together. Individuals harboring the Lys751Gln_CC/Gly156Gly_CC genotype were significantly over-represented among late-onset melanoma cases (OR=1.7, p<0.05). The results of analyses of linkage disequilibrium and haplotype frequency support the thesis that a combination of at least two SNPs (Lys751Gln_CC/Gly156Gly_CC or Lys751Gln_CC/Asp312Asn_AA) inherited as a haplotype was associated with disease. These two pairs of SNPs could therefore be regarded as a single hereditary unit that would have a very small probability of being disrupted by recombination. Additional studies are required to determine whether these particular changes can be associated with an increased risk of other malignancies at different sites of origin.