Witherspoon D J, Marchani E E, Watkins W S, Ostler C T, Wooding S P, Anders B A, Fowlkes J D, Boissinot S, Furano A V, Ray D A, Rogers A R, Batzer M A, Jorde L B
Department of Human Genetics, University of Utah Health Sciences Center, Salt Lake City, UT 84112-5330, USA.
Hum Hered. 2006;62(1):30-46. doi: 10.1159/000095851. Epub 2006 Sep 21.
BACKGROUND/AIMS: The L1 retrotransposable element family is the most successful self-replicating genomic parasite of the human genome. L1 elements drive replication of Alu elements, and both have had far-reaching impacts on the human genome. We use L1 and Alu insertion polymorphisms to analyze human population structure.
We genotyped 75 recent, polymorphic L1 insertions in 317 individuals from 21 populations in sub-Saharan Africa, East Asia, Europe and the Indian subcontinent. This is the first sample of L1 loci large enough to support detailed population genetic inference. We analyzed these data in parallel with a set of 100 polymorphic Alu insertion loci previously genotyped in the same individuals.
The data sets yield congruent results that support the recent African origin model of human ancestry. A genetic clustering algorithm detects clusters of individuals corresponding to continental regions. The number of loci sampled is critical: with fewer than 50 typical loci, structure cannot be reliably discerned in these populations. The inclusion of geographically intermediate populations (from India) reduces the distinctness of clustering. Our results indicate that human genetic variation is neither perfectly correlated with geographic distance (purely clinal) nor independent of distance (purely clustered), but a combination of both: stepped clinal.
背景/目的：L1反转录转座元件家族是人类基因组中最成功的自我复制基因组寄生虫。L1元件驱动Alu元件的复制，二者都对人类基因组产生了深远影响。我们利用L1和Alu插入多态性来分析人类群体结构。
我们对来自撒哈拉以南非洲、东亚、欧洲和印度次大陆21个群体的317名个体中的75个近期多态性L1插入进行了基因分型。这是首个足够大以支持详细群体遗传学推断的L1基因座样本。我们将这些数据与先前在同一批个体中基因分型的一组100个多态性Alu插入基因座的数据并行分析。
数据集得出了一致的结果，支持人类祖先的近期非洲起源模型。一种遗传聚类算法检测到了对应于大陆区域的个体聚类。所采样的基因座数量至关重要：少于50个典型基因座时，无法在这些群体中可靠地辨别结构。纳入地理上处于中间位置的群体（来自印度）会降低聚类的明显程度。我们的结果表明，人类遗传变异既不完全与地理距离相关（纯粹渐变），也不与距离无关（纯粹聚类），而是二者的结合：阶梯渐变。
