Brown M D, Hosseini S H, Torroni A, Bandelt H J, Allen J C, Schurr T G, Scozzari R, Cruciani F, Wallace D C
Center for Molecular Medicine, Emory University School of Medicine, Atlanta, GA, USA.
Am J Hum Genet. 1998 Dec;63(6):1852-61. doi: 10.1086/302155.
On the basis of comprehensive RFLP analysis, it has been inferred that approximately 97% of Native American mtDNAs belong to one of four major founding mtDNA lineages, designated haplogroups "A"-"D." It has been proposed that a fifth mtDNA haplogroup (haplogroup X) represents a minor founding lineage in Native Americans. Unlike haplogroups A-D, haplogroup X is also found at low frequencies in modern European populations. To investigate the origins, diversity, and continental relationships of this haplogroup, we performed mtDNA high-resolution RFLP and complete control region (CR) sequence analysis on 22 putative Native American haplogroup X and 14 putative European haplogroup X mtDNAs. The results identified a consensus haplogroup X motif that characterizes our European and Native American samples. Among Native Americans, haplogroup X appears to be essentially restricted to northern Amerindian groups, including the Ojibwa, the Nuu-Chah-Nulth, the Sioux, and the Yakima, although we also observed this haplogroup in the Na-Dene-speaking Navajo. Median network analysis indicated that European and Native American haplogroup X mtDNAs, although distinct, nevertheless are distantly related to each other. Time estimates for the arrival of X in North America are 12,000-36,000 years ago, depending on the number of assumed founders, thus supporting the conclusion that the peoples harboring haplogroup X were among the original founders of Native American populations. To date, haplogroup X has not been unambiguously identified in Asia, raising the possibility that some Native American founders were of Caucasian ancestry.
基于全面的限制性片段长度多态性（RFLP）分析，据推断，大约97%的美洲原住民线粒体DNA（mtDNA）属于四个主要的奠基性mtDNA谱系之一，即单倍群“A”-“D”。有人提出，第五个mtDNA单倍群（单倍群X）代表了美洲原住民中的一个次要奠基谱系。与单倍群A - D不同，单倍群X在现代欧洲人群中也有低频率出现。为了研究这个单倍群的起源、多样性和大陆间关系，我们对22个假定的美洲原住民单倍群X和14个假定的欧洲单倍群X的mtDNA进行了高分辨率RFLP分析和完整控制区（CR）序列分析。结果确定了一个共同的单倍群X基序，它是我们欧洲和美洲原住民样本的特征。在美洲原住民中，单倍群X似乎基本上局限于北美印第安人群体，包括奥吉布瓦人、努-查-努尔特人、苏族人以及亚基马人，不过我们在说纳-德内语的纳瓦霍人中也观察到了这个单倍群。中介网络分析表明，欧洲和美洲原住民的单倍群X mtDNA虽然不同，但彼此之间存在远缘关系。根据假定奠基者的数量，X到达北美的时间估计在12000 - 36000年前，这支持了这样的结论，即携带单倍群X的人群是美洲原住民群体的原始奠基者之一。迄今为止，在亚洲尚未明确鉴定出单倍群X，这增加了一些美洲原住民奠基者具有高加索血统的可能性。
