Bendall K E, Macaulay V A, Sykes B C
Department of Cellular Science, University of Oxford, United Kingdom.
Am J Hum Genet. 1997 Dec;61(6):1303-8. doi: 10.1086/301636.
During direct sequencing of the first hypervariable segment of the human mitochondrial control region, we identified one individual with a heteroplasmic point mutation at nt 16,256. We used primer extension to analyze the proportions of each mitochondrial haplotype in peripheral blood, buccal cells, and single hair roots from this individual and from eight members of his maternal lineage. Significant levels of heteroplasmy were found in only three individuals, and, in these cases, the proportions of each haplotype were similar in both blood and buccal cells. From the changes in mitochondrial haplotypes within mother-offspring pairs, we calculated that the most likely size of a mitochondrial bottleneck during development was 1-27 segregating units. However, highly variable levels of heteroplasmy were found in single hair roots, even among roots from the same individual. We analyzed a large number of hair roots from one individual and found that the proportion of one haplotype was within a range of 9% to > 99% in different roots. Roots originating from within a small patch of skin had haplotype proportions as variable as those from different areas of skin.
在对人类线粒体控制区第一个高变区进行直接测序时，我们鉴定出一名个体，其在核苷酸16,256处存在异质性点突变。我们使用引物延伸法分析了该个体及其母系谱系中八名成员的外周血、颊黏膜细胞和单根毛发中每种线粒体单倍型的比例。仅在三名个体中发现了显著水平的异质性，并且在这些情况下，每种单倍型在血液和颊黏膜细胞中的比例相似。根据母-子对中线粒体单倍型的变化，我们计算出发育过程中线粒体瓶颈的最可能大小为1 - 27个分离单位。然而，即使在同一个体的毛发根部之间，单根毛发中也发现了高度可变的异质性水平。我们分析了一名个体的大量毛发根部，发现不同根部中一种单倍型的比例在9%至> 99%的范围内。源自一小片皮肤区域内的毛发根部，其单倍型比例与来自不同皮肤区域的毛发根部一样具有变异性。
