Demonstration of the 4977 bp deletion in human mitochondrial DNA from intravital and postmortem blood

The 4977 bp deletion in mitochondrial DNA (mtDNA) is known to accumulate wi th age in various human tissues. Findings regarding its accumulation in blo od, however, have so far been contradictory. We investigated the levels of the 4977 bp deletion in mtDNA from 100 intravital and postmortem blood samp les. Applying an improved version of a PCR plus silver staining of polyacry lamide gels, we could detect the 4977 bp deletion in blood of healthy indiv iduals over 20 years of age. While the 4977 bp deletion in blood is subject to a certain age dependence, it appears to be influenced by additional fac tors. A Primer-Shift-Assay amplifying four different deletion-specific frag ments showed that the smaller fragments were amplified with a higher amplif ication efficiency than the larger fragments. The deletion-specific 389 bp fragment was demonstrated in 73% of individuals over 80 years of age, but i n only 46% of individuals between 21 and 30 years old whereas the largest 8 02 bp deletion-specific fragment was detectable in 38% of subjects over 80 years of age, and in only 15% of individuals under 30 years of age. Deletio n-specific fragments were not detected in a single individual under 20 year s old, nor in fetal blood. In this work, we demonstrate for the first time the detection of 4977 bp specific fragments in blood of healthy individuals without the necessity of using a nested PCR. The deletion is detectable in postmortal and intravital blood, so that the occurrence of the 4977 bp del etion seems to be a physiological and not only a postmortal process. (C) 19 98 Elsevier Science B.V. All rights reserved.