Darker skin pigmentation links to fewer mitochondrial DNA mutations from sun exposure

In an observational study of six older men, researchers analyzed how skin pigmentation influences mitochondrial DNA (mtDNA) stability under chronic sun exposure. The team performed targeted mitochondrial sequencing on paired skin biopsies from the photoexposed forearms and photoprotected buttocks of three Black African and three White Northern European participants. They identified 21 high-confidence somatic mtDNA variants across the samples. Photoexposed light skin possessed six-fold more variants than dark skin and was enriched for ultraviolet radiation signatures, such as C>T transitions and CC>TT substitutions. These variants in light skin altered multiple oxidative phosphorylation genes and frequently reached moderate-to-high heteroplasmy. Conversely, dark skin displayed a narrower variant profile dominated by a recurrent T414G substitution and lower overall heteroplasmy.