Science2014-06-16 2:57 PM

为医疗目的而细细梳理墨西哥人的遗传基因 The genetics of Mexico recapitulates Native American substructure and affects biomedical traits

论文摘要 

研究人员对墨西哥人的遗传学进行了认真钻研;他们的精细尺度的研究是首个在该地区进行该类研究,该研究揭示了现代墨西哥人的基因组是如何受到古代美洲原住民的人口动态变化影响的;美洲原住民指的是那些在欧洲殖民前就住在该地区的人。据该研究报告指出,确实,尽管在过去的500年中发生了与欧洲殖民活动有关的人群混合——或异种交配,但原住民的基因痕迹在现代人群中仍很强劲。这可帮助医生为当今的医学遗传学研究进行定制和解读。墨西哥拥有世界上最大的美洲原住民群体之一,而美洲原住民只是促成目前拉丁美洲人群和美国西语裔人群的几个主要的民族群体之一。这一人群含有的某些遗传变异是所有大陆人群中所见的最少的,但在各个亚群之间则有着明显的差异;因此,有原住民血统的人可能含有十分罕见的遗传变异,其中包括那些与医学有关的遗传变异。

先前对本土墨西哥人遗传多样性的估计一直局限于小样本。如今,为了在了解精细尺度的墨西哥国内的基因组进化模式上取得进步,Andrés Moreno-Estrada 等人呈示了也许是迄今最大的有关原住民人群的基因组数据集。他们对来自20个原住民人群中的511个本土墨西哥人的基因组数据进行了评估。他们的分析代表了墨西哥大多数的地理区域;该分析侧重于被称为单核苷酸多态性的DNA序列变异。应用该分析,研究人员对欧洲殖民之前墨西哥内的多个人群的遗传学进行了描述,并指出他们中有许多具有非常独特的基因组成,其程度远远超过在欧洲的情况。这些差别中的某些甚至比欧洲人与亚洲人之间的差别还更高,提示墨西哥境内的早期人群是高度隔离的。在欧洲人到来后,墨西哥内的人口动态变化有了明显的改变。如今的墨西哥人大多数有着混合的血统。研究人员通过将来自墨西哥10个州的500名本土墨西哥人群中的欧洲与印地安人混血个体以及生活在更远的瓜达拉哈拉和洛杉矶的墨西哥人的人群资料进行结合来研究这种情况。他们进行了一个演算法来估测这些个体中的祖先基因比例,并发现,老的基因模式在现代墨西哥人群中继续存留着,例如,来自墨西哥北方各州的人显示出了最高比例的北部土著人的基因组成分。与此同时,墨西哥裔美国人则没有显示这一模式,这与他们是从墨西哥各地来到美国的这一事实是一致的。研究人员还基于地理揭示了在原住民血统程度与肺部健康之间的一种相关性。这项工作在精密医学中有潜在的功用;也就是说,它可用于发现可能会影响肺功能的遗传变异。这一努力超越了对疾病相关性变异株进行宽泛的观察;为了更好的临床转归,可专注于罕见、医学相关的人群特异性遗传变异。

Abstract 

Mexico harbors great cultural and ethnic diversity, yet fine-scale patterns of human genome-wide variation from this region remain largely uncharacterized. We studied genomic variation within Mexico from over 1000 individuals representing 20 indigenous and 11 mestizo populations. We found striking genetic stratification among indigenous populations within Mexico at varying degrees of geographic isolation. Some groups were as differentiated as Europeans are from East Asians. Pre-Columbian genetic substructure is recapitulated in the indigenous ancestry of admixed mestizo individuals across the country. Furthermore, two independently phenotyped cohorts of Mexicans and Mexican Americans showed a significant association between subcontinental ancestry and lung function. Thus, accounting for fine-scale ancestry patterns is critical for medical and population genetic studies within Mexico, in Mexican-descent populations, and likely in many other populations worldwide.

Editor's Summary

The population structure of Native Mexicans

The genetics of indigenous Mexicans exhibit substantial geographical structure, some as divergent from each other as are existing populations of Europeans and Asians. By performing genome-wide analyses on Native Mexicans from differing populations, Moreno-Estrada et al. successfully recapitulated the pre-Columbian substructure of Mexico. This ancestral structure is evident among cosmopolitan Mexicans and is correlated with subcontinental origins and medically relevant aspects of lung function. These findings exemplify the importance of understanding the genetic contributions of admixed individuals.

Science, this issue p. 1280
( http://www.sciencemag.org/content/344/6189/1280 )

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