Pallotti F, Chen X, Bonilla E, Schon E A
Department of Neurology, Columbia University, New York, USA.
Am J Hum Genet. 1996 Sep;59(3):591-602.
It is unclear at present whether specific mtDNA point mutations accumulate during normal human aging. In order to address this question, we used quantitative PCR of total DNA isolated from skeletal muscle from normal individuals of various ages to search for the presence and amount of spontaneous mtDNA point mutations in two small regions of the human mitochondrial genome. We observed low levels of somatic mutations above background in both regions, but there was no correlation between the amount of mutation detected and the age of the subject. These results contrasted with our finding of an age-related increase in the amount of the mtDNA "common deletion" in these very samples. Thus, it appears that both somatic mtDNA point mutations and mtDNA deletions can arise at low frequency in normal individuals but that, unlike deletions, there is no preferential amplification or accumulation of specific point mutations in skeletal muscle over the course of the normal human life span.
目前尚不清楚在正常人类衰老过程中是否会积累特定的线粒体DNA（mtDNA）点突变。为了解决这个问题，我们对从不同年龄正常个体的骨骼肌中分离出的总DNA进行了定量PCR，以寻找人类线粒体基因组两个小区域中自发mtDNA点突变的存在情况和数量。我们在两个区域均观察到高于背景水平的低水平体细胞突变，但检测到的突变数量与受试者年龄之间没有相关性。这些结果与我们在这些相同样本中发现的mtDNA“常见缺失”数量随年龄增长而增加的情况形成对比。因此，似乎体细胞mtDNA点突变和mtDNA缺失在正常个体中都可能以低频率出现，但与缺失不同的是，在正常人类寿命过程中，骨骼肌中特定点突变没有优先扩增或积累。
