The Gln/Gln genotype of XPD codon 751 as a genetic marker for melanoma risk and Lys/Gln as an important predictor for melanoma progression: a case control study in the Swedish population

The Xeroderma pigmentosum complementation group D (XPD) is a critical protein in the nucleotide excision repair system for DNA damage. Genetic variations in XPD exert an important effect on the capacity of DNA repair. In this study, we examined Lys751Gln polymorphism at the XPD gene in 244 melanoma patients and 251 healthy individuals (as controls) from the south-eastern region of Sweden. The associations of polymorphism with melanoma risk, as well as with melanoma features and pigment phenotypes of the melanoma patients were analysed. DNA was extracted from the mononuclear cells of venous blood of the melanoma patients and controls. XPD codon 751 was genotyped by the PCR restriction fragment length polymorphism technique. Results showed that there was no difference in the distribution of the XPD codon 751 genotypes between the melanoma patients and healthy controls. However, the Gln/Gln genotype was found to be associated with melanoma risk in the male population. Furthermore, the frequency of the Gln/Gln genotype was significantly higher in the early stages of melanomas, whereas Lys/Gln was more frequent in the later stages and in the patients with melanoma located on intermittently UV-exposed areas. No correlations between the polymorphisms and phenotypes of the patients were found. In conclusion, Gln/Gln was a useful genetic marker for melanoma risk in the males, while Lys/Gln was an important predictor for melanoma progression.