Lactase Persistence Alleles Reveal Partial East African Ancestry of Southern African Khoe Pastoralists
Lactase Persistence Alleles Reveal Partial East African Ancestry of Southern African Khoe Pastoralists
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DOI：
10.1016/j.cub.2014.02.041
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发表时间：
2014-04-14
期刊：
影响因子：
9.2
通讯作者：
Jakobsson, Mattias
中科院分区：
文献类型：
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作者：
Breton, Gwenna;Schlebusch, Carina M.;Jakobsson, Mattias
成年期消化牛奶的能力、乳糖酶持久性 (LP) 以及与 LP 相关的特定遗传变异在全球人群中分布不均 [1-4]。当一些人群从狩猎采集生活方式转变为牧民或农耕生活方式时，这些变体最有可能成为选择的目标[5-7]。特定的 LP 多态性与特定的地理区域和人群相关 [1-4, 8-10]；然而，南部非洲尚未对它们进行广泛研究。我们对来自 13 个南部非洲人群（包括狩猎采集者、牧民和农牧民的后裔）的 267 名个体的 LP 调节区域进行了调查，首次对一大群南部非洲人的 LP 调节区域进行了全面研究。 “东非”LP 单核苷酸多态性 (SNP) (14010G>C) 在严格的牧民 Khoe 人群（纳米比亚的 Nama）中以高频率 (>20%) 被发现，表明与东非有联系，而“欧洲”LP SNP (13910C>T) 在混合血统人群中发现。利用来自不同非洲人群的全基因组数据，我们确定了纳马人中的混合物（13%），来自一个可追溯到 1,300 多年前的亚非族群，其基因组的其余部分来自桑族狩猎采集者。我们还发现了科伊语群体中围绕 LCT 基因进行选择的证据，而 14010C 变体在纳马人中的大量出现频率最好的解释是对消化牛奶的适应。这些基因组局部和全基因组结果支持了一个模型，在该模型中，一个东非群体将游牧习俗带到了南部非洲，并与当地的狩猎采集者混合，形成了科伊人的祖先。
The ability to digest milk into adulthood, lactase persistence (LP), as well as specific genetic variants associated with LP, is heterogeneously distributed in global populations [1-4]. These variants were most likely targets of selection when some populations converted from hunter-gatherer to pastoralist or farming lifestyles [5-7]. Specific LP polymorphisms are associated with particular geographic regions and populations [1-4, 8-10]; however, they have not been extensively studied in southern Africa. We investigate the LP-regulatory region in 267 individuals from 13 southern African populations (including descendants of hunter-gatherers, pastoralists, and agropastoralists), providing the first comprehensive study of the LP-regulatory region in a large group of southern Africans. The "East African" LP single-nucleotide polymorphism (SNP) (14010G>C) was found at high frequency (>20%) in a strict pastoralist Khoe population, the Nama of Namibia, suggesting a connection to East Africa, whereas the "European" LP SNP (13910C>T) was found in populations of mixed ancestry. Using genome-wide data from various African populations, we identify admixture (13%) in the Nama, from an Afro-Asiatic group dating to >1,300 years ago, with the remaining fraction of their genomes being from San hunter-gatherers. We also find evidence of selection around the LCT gene among Khoe-speaking groups, and the substantial frequency of the 14010C variant among the Nama is best explained by adaptation to digesting milk. These genome-local and genome-wide results support a model in which an East African group brought pastoralist practices to southern Africa and admixed with local hunter-gatherers to form the ancestors of Khoe people.