A specific 4977-bp deletion of mitochondrial DNA in human ageing skin.

Mitochondrial DNA (mtDNA) mutations have recently been proposed as important contributors to ageing and degenerative diseases. In this study, we applied the polymerase chain reaction technique to detect 4.977 bp-deleted mtDNA, the most common and abundant deletion of mtDNA, in normal human skin. None of the skin specimens from patients less than 60 years of age were found to bear this type of mtDNA deletion. The incidence of the 4977-bp-deleted mtDNA increased with advancing age. The incidence of the deletion was 20%, 46.7% and 83.4% for patients of the age groups of 61-70, 71-80, and 81-90 years, respectively. Moreover, the incidence of 4977-bp-deleted mtDNA was significantly higher in exposed skin than that in non-exposed skin. We suggest that mtDNA mutations are molecular events associated with the human skin ageing process.