Genomic mutation landscape of skin cancers from DNA repair-deficient xeroderma pigmentosum patients

Xeroderma pigmentosum (XP) is a genetic disorder caused by mutations in genes of the Nucleotide Excision Repair (NER) pathway (groups A-G) or in Translesion Synthesis DNA polymerase eta (V). XP is associated with an increased skin cancer risk, reaching, for some groups, several thousand-fold compared to the general population. Here, we analyze 38 skin cancer genomes from five XP groups. We find that the activity of NER determines heterogeneity of the mutation rates across skin cancer genomes and that transcription-coupled NER extends beyond the gene boundaries reducing the intergenic mutation rate. Mutational profile in XP-V tumors and experiments with POLH knockout cell line reveal the role of polymerase eta in the error-free bypass of (i) rare TpG and TpA DNA lesions, (ii) 3' nucleotides in pyrimidine dimers, and (iii) TpT photodimers. Our study unravels the genetic basis of skin cancer risk in XP and provides insights into the mechanisms reducing UV-induced mutagenesis in the general population. Xeroderma pigmentosum (XP) is a rare genetic disorder that is associated with a higher risk of skin cancer. Here, the authors analyse the genomes of skin cancers from patients across five different XP groups, revealing genetic and molecular factors related to the mutational profile and UV-related mutagenesis in XP.

Automated summary

Xeroderma pigmentosum (XP) is a rare genetic disorder associated with an increased risk of skin cancer. In this study, the authors analyze skin cancer genomes from five different XP groups, revealing genetic and molecular factors related to the mutational profile and UV-induced mutagenesis in XP.