The Incidence of Both Tandem Duplications and the Common Deletion in mtDNA from Three Distinct Categories of Sun-Exposed Human Skin and in Prolonged Culture of Fibroblasts

The use of mtDNA damage as a biomarker of cumulative sunlight exposure in human skin is a relatively new field of research. Previous investigations have simply compared the frequency of occurrence of the mtDNA common deletion (CD), and to a much lesser extent that of tandem duplications (TDs), to distinguish between sun-protected and sun-exposed skin. This approach is limited because non-melanoma skin cancer is predominantly formed on body sites that are “usually” sun-exposed as opposed to sites that are “occasionally” sun-exposed and as such they differ in their cumulative UV exposure. This study addresses this limitation by investigating the frequency of occurrence of the CD and TDs in 116 age-matched human skin samples taken from three different sun-exposed body sites. There was a greater frequency of the mtDNA damage in “usually” sun-exposed compared to “occasionally” sun-exposed body sites for both the CD and the TDs (P