Whole exome-sequencing of vitiligo lesions indicate lower burden of somatic variations: implications in risk for non-melanoma skin cancers

Mapping of somatic variations has enabled understanding the progression of clonal variations from healthy skin to cutaneous malignancies. Highlighting, the adaptive nature of pigmentation, germline mutations in albinism amplify skin cancer susceptibility. However, lower incidence of non-melanoma skin cancer among subjects with acquired depigmenting skin disorder vitiligo is enigmatic and a matter of longstanding debate. To address this, we performed high-coverage exome sequencing of matched non-lesional and lesional vitiligo skin along with whole blood to account for germline variations. Our analysis suggests lower burden of somatic cancer-associated variations in exposed depigmented lesional skin compared to the non-lesional skin. A detailed investigation of vitiligo skin transcriptome reveals elevation of DNA repair and cell-proliferation pathways. Validation by comet-assay for DNA damage and cell cycle analysis of epidermal cells suggest undamaged DNA in vitiligo lesions that could be attributed to higher proliferation-coupled repair. Endorsing this, UV-signature variations are not prominent, instead SBS5 associated with endogenous mutational processes is conspicuous in both the vitiligo tissues. Our systematic pilot study indicates lower somatic mutation burden in vitiligo skin and supports the earlier demographic observation on lower risk of non-melanoma skin cancer in vitiligo subjects, providing an opportunity to learn strategies for cancer prevention from vitiligo. Brief SummaryVitiligo skin harbors decreased somatic variation burden in cancer-associated genes and a concomitant augmentation in DNA repair response, explaining the lower incidence of cutaneous malignancies.