随着大量线粒体DNA（mtDNA）全基因组信息的积累，东亚人群的母系遗传结构已经得到较为清晰的认识。然而，研究中仍发现有一些mtDNA类型无法识别，虽然这些未定类型的分布频率很低，但其系统发育地位究竟如何迄今仍不得而知。与此同时，由于东亚具有丰富且较为连续的古人类（the archaic hominid）化石记录，该地区人群因而被认为可能为独立起源或存在来自古人类的遗传贡献。虽然该观点被来自Y染色体的研究工作所否定，但不同的声音认为，Y染色体研究仅能从父系角度排除该可能性，并不能否定存在母系贡献的可能。显然，如果现代东亚人群中确实存在源自古人类的母系遗传贡献，那么这些类型则很可能分布于那些低频且迄今无法确定其系统发育地位的mtDNA类型之中。
为了解决这个问题，中科院昆明动物研究所孔庆鹏研究员与张亚平院士课题组合作对东亚人群进行了大规模研究。通过收集分析了采自84个中国人群6000余份样本的mtDNA序列，从中甄别出近200个未定类型，采用mtDNA全基因组测序等手段确定所有未定类型的系统发育地位，并将结果应用于其它已发表的5000余份东亚人群mtDNA序列数据。研究结果揭示，迄今甄别出来的mtDNA未定类型事实上均源自非洲起源的建群类型M或N，没有发现可能追溯至古人类的母系遗传组份。进一步分析还提示，研究中新鉴别的基部类群很可能代表了最初进入东亚南部的现代人群祖先的母系遗存，而非来自邻近地区（例如东南亚）的近期基因流。考虑到这些基部类群主要集中分布在中国南部，提示该区域很可能是现代人类祖先进入东亚后的主要聚集及分化地。该项研究工作是双方继中国藏族的起源等研究之后又一共同完成的研究成果，目前已在线发表在国际重要期刊《分子生物与进化》（Mol Biol Evol）上。（生物谷Bioon.com）
生物谷推荐原文出处：
Molecular Biology and Evolution, doi:10.1093/molbev/msq219
Large-scale mtDNA screening reveals a surprising matrilineal complexity in East Asia and its implications to the peopling of the region
Qing-Peng Kong1,2,*, Chang Sun1, Hua-Wei Wang3, Mian Zhao1,2, Wen-Zhi Wang1,2, Li Zhong3, Xiao-Dan Hao1,2, Hui Pan1,2, Sha-Yan Wang4, Yao-Ting Cheng1,2, Chun-Ling Zhu1, Shi-Fang Wu1, Li-Na Liu1, Jie-Qiong Jin1, Yong-Gang Yao5 and Ya-Ping Zhang1,2,3,*
1 State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
2 KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming 650223, China
3 Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China
4 Shenzhen People's Hospital, Clinical Medical College of Jinan University, Shenzhen 518020, China
5 Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
In order to achieve a thorough coverage of the basal lineages in the Chinese matrilineal pool, we have sequenced the mitochondrial DNA (mtDNA) control region and partial coding-region segments of 6,093 mtDNAs sampled from 84 populations across China. By comparing with the available complete mtDNA sequences, 194 of those mtDNAs could not be firmly assigned into the available haplogroups. Completely sequencing 51 representatives selected from these unclassified mtDNAs identified a number of novel lineages, including five novel basal haplogroups that directly emanate from the Eurasian founder nodes (M and N). No matrilineal contribution from the archaic hominid was observed. Subsequent analyses suggested that these newly identified basal lineages likely represent the genetic relics of modern humans initially peopling East Asia, instead of being the results of gene flow from the neighboring regions. The observation that most of the newly recognized mtDNA lineages have already differentiated and show the highest genetic diversity in southern China provided additional evidence in support of the Southern-Route peopling hypothesis of East Asians. Specifically, the enrichment of most of the basal lineages in southern China and their rather ancient ages in Late Pleistocene further suggested that this region was likely the genetic reservoir of modern humans after they entered East Asia.
