XPD exon 10 and 23 polymorphisms and DNA repair in human skin in situ

Forty-four Finnish volunteers who were previously studied with regard to th e repair rate of UV-specific cyclobutane pyrimidine dimers in the skin were genotyped for XPD polymorphisms at codons 312 (exon 10 G -->A, Asp --> Asn ) and 751 (exon 23 A -->C, Lys --> Gln). The repair rate was measured at 24 h for two different cyclobutane dimers. The data did not show consistent X PD genotype-specific differences in DNA repair rates among all subjects. Th e combined exon 10 AA and exon 23 CC genotype was associated with an simila r to 50% depression of repair rate but this was of borderline statistical s ignificance. However, the exon 23 C allele was associated with depressed re pair among subjects aged 50 years or older and the result was consistent wi th both dimers.