DETECTION OF THE AGE-DEPENDENT 4977-BP DELETION OF MITOCHONDRIAL-DNA - A PILOT-STUDY

In recent years a number of mitochondrial DNA (mtDNA) deletions have b een detected in various tissues from individuals over 20 years of age. It has been postulated that these deletions are associated with natur al aging. In order to determine whether a correlation exists between a ge and the amount of deleted 4977 bp mtDNA, we used two PCR reactions to study total DNA (nuclear and mitochondrial DNA) extracted from skel etal muscle (m. iliopsoas) obtained at autopsy from 93 individuals rep resenting a wide age spectrum (range: 3 months-97 years). The primer p air L15/H15 was used to amplify a 533 bp fragment of intact mtDNA to d etermine the percentage of total DNA. A second PCR with the primer pai r L35/H35 was then employed to amplify a 667 bp fragment of the delete d mtDNA. The amount of template DNA necessary to amplify the specific fragments of deleted mtDNA was found to decrease with age. Whereas no 4977 bp deletion could be detected in subjects under 20 years of age e ven with 1000 ng of total DNA, in individuals aged 21 to 30 years 1000 ng total DNA were sufficient. Only 1 ng total DNA was needed in all i ndividuals over 70. Our results show that the 4977 bp deletion can be a useful marker of natural aging in human subjects.