No association between three xeroderma pigmentosum group C and one group G gene polymorphisms and risk of cutaneous melanoma

Xeroderma pigmentosum (XP) patients exhibit a 1000-fold increased risk for developing skin cancers including malignant melanoma. We investigated the role of three variant alleles of the DNA repair gene XPC and one variant allele of the XPG gene in a hospital-based case-control study of 294 Caucasian patients from Germany with malignant melanoma and 375 healthy control individuals from the same area matched by sex. The polymorphisms G1580A (XPC exon 8; Arg492His), T1601C (XPC exon 8; Val499Ala), G2166A (XPC exon 10; Arg687Arg), and C3507G ( XPG exon 15; Asp1104His) were not in linkage disequilibrium. The allele frequencies ( cases: controls) were for 1580A 6.29%: 5.63%, for 1601C 79.08%: 78.28%, for 2166A 26.19%: 28.13%, and for 3507G 79.86%: 78.61%. We found no association of the homozygous 1580A, 1601C, 2166A, and 3507G genotypes with increased risks of melanoma: OR 1.254 (95% CI: 0.486 - 3.217), OR 1.108 ( 95% CI: 0.629 - 1.960), OR 0.817 ( 95% CI: 0.490 - 1.358), and OR 1.168 ( 95% CI: 0.670 - 2.044), respectively. Exploratory analyses of subgroups of melanoma patients compared to all controls indicated no association of these genotypes with increased risks for development of multiple primary melanomas (n = 28), a negative family history for melanoma ( n = 277), melanomas in individuals with a low number of nevi ( n = 273), melanomas in individuals older than 55 years ( n = 142), and melanomas thicker than 1 mm ( n = 126).