Riccio Maria Eugenia, Nunes José Manuel, Rahal Melissa, Kervaire Barbara, Tiercy Jean-Marie, Sanchez-Mazas Alicia
Laboratory of Anthropology, Genetics, and Peopling History (AGP), Laboratory of Anthropology, Genetics, and Peopling History (AGP), Anthropology Unit, Department of Genetics and Evolution, University of Geneva, Switzerland.
Hum Biol. 2011 Jun;83(3):405-35. doi: 10.3378/027.083.0306.
The Austroasiatic linguistic family disputes its origin between two geographically distant regions of Asia, India, and Southeast Asia, respectively. As genetic studies based on classical and gender-specific genetic markers provided contradictory results to this debate thus far, we investigated the HLA diversity (HLA-A, -B, and -DRB1 loci) of an Austroasiatic Munda population from Northeast India and its relationships with other populations from India and Southeast Asia. Because molecular methods currently used to test HLA markers often provide ambiguous results due to the high complexity of this polymorphism, we applied two different techniques (reverse PCR-SSO typing on microbeads arrays based on Luminex technology, and PCR-SSP typing) to type the samples. After validating the resulting frequency distributions through the original statistical method described in our companion article ( Nunes et al. 2011 ), we compared the HLA genetic profile of the sampled Munda to those of other Asiatic populations, among which Dravidian and Indo-European-speakers from India and populations from East and Southeast Asia speaking languages belonging to different linguistic families. We showed that the Munda from Northeast India exhibit a peculiar genetic profile with a reduced level of HLA diversity compared to surrounding Indian populations. They also exhibit less diversity than Southeast Asian populations except at locus DRB1. Several analyses using genetic distances indicate that the Munda are much more closely related to populations from the Indian subcontinent than to Southeast Asian populations speaking languages of the same Austroasiatic linguistic family. On the other hand, they do not share a closer relationship with Dravidians compared with Indo-Europeans, thus arguing against the idea that the Munda share a common and ancient Indian origin with Dravidians. Our results do not favor either a scenario where the Munda would be representative of an ancestral Austroasiatic population giving rise to an eastward Austroasiatic expansion to Southeast Asia. Rather, their peculiar genetic profile is better explained by a decrease in genetic diversity through genetic drift from an ancestral population having a genetic profile similar to present-day Austroasiatic populations from Southeast Asia (thus suggesting a possible southeastern origin), followed by intensive gene flow with neighboring Indian populations. This conclusion is in agreement with archaeological and linguistic information. The history of the Austroasiatic family represents a fascinating example where complex interactions among culturally distinct human populations occurred in the past.
南亚语系在亚洲两个地理上相距遥远的地区，即印度和东南亚，探寻其起源。迄今为止，基于经典和性别特异性遗传标记的基因研究为这场争论提供了相互矛盾的结果，因此我们调查了印度东北部一个南亚语系蒙达族群体的HLA多样性（HLA-A、-B和-DRB1基因座），以及它与印度和东南亚其他群体的关系。由于目前用于检测HLA标记的分子方法常常因这种多态性的高度复杂性而产生模糊结果，我们应用了两种不同技术（基于Luminex技术的微珠阵列上的反向PCR-SSO分型，以及PCR-SSP分型）对样本进行分型。通过我们配套文章（努内斯等人，2011年）中描述的原始统计方法验证所得频率分布后，我们将抽样的蒙达族群体的HLA基因谱与其他亚洲群体的进行了比较，其中包括来自印度的达罗毗荼语系和印欧语系使用者，以及来自东亚和东南亚、说不同语系语言的群体。我们发现，与周边印度群体相比，印度东北部的蒙达族群体呈现出独特的基因谱，HLA多样性水平降低。除了DRB1基因座外，他们的多样性也低于东南亚群体。几项使用遗传距离的分析表明，蒙达族群体与印度次大陆的群体关系比与说同一南亚语系语言的东南亚群体更为密切。另一方面，与印欧语系使用者相比，他们与达罗毗荼语系使用者的关系并不更密切，因此反对蒙达族群体与达罗毗荼语系使用者有共同且古老的印度起源这一观点。我们的结果不支持蒙达族群体代表一个祖先南亚语系群体、引发了向东扩展至东南亚的南亚语系扩张这一设想。相反，他们独特的基因谱更好的解释是，一个基因谱与当今东南亚南亚语系群体相似的祖先群体通过遗传漂变导致遗传多样性降低（因此暗示可能起源于东南部），随后与邻近的印度群体有大量基因流动。这一结论与考古学和语言学信息一致。南亚语系的历史代表了一个引人入胜的例子，说明过去文化上不同的人类群体之间发生了复杂的相互作用。
