一种用于区分西非人、非洲裔美国人和欧洲裔美国人的基因型分析可能帮助科学家理解各个人群的世系，并且通过遗传倾向研究健康与医药。
Sarah Tishkoff及其同事使用来自西非人、非洲裔美国人和欧洲裔美国人的高密度基因型数据从而研究了它们是否能够可靠地区分各个西非人群并确定非洲裔美国人的具体非洲祖先世系。这组作者发现，尽管一些西非人群几乎无法区分，被语言和地理界限分隔的一些群体存在可以辨识的遗传差异。这项研究还凸显了非洲裔美国人祖先世系如同丰富的马赛克一般，此前还没有被很好地记录下来。在该研究的365名非洲裔美国人中，个体的西非祖先世系在99%到小于1%之间。非洲裔美国人的西非成分最类似于非班图、说尼日尔一科尔多凡语的人群的遗传谱，这符合跨大西洋奴隶贸易的历史记载。这组科学家提出，他们的技术——这种技术经过了修改从而增加了遗传标记的密度——最终可能更准确地弄清非洲裔美国人的祖先世系。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS December 14, 2009, doi: 10.1073/pnas.0909559107
Genome-wide patterns of population structure and admixture in West Africans and African Americans
Katarzyna Bryca, Adam Autona, Matthew R. Nelsonb, Jorge R. Oksenbergc, Stephen L. Hauserc, Scott Williamsd, Alain Fromente, Jean-Marie Bodof, Charles Wambebeg, Sarah A. Tishkoffh,1,2 and Carlos D. Bustamantea,1,3
aDepartment of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY 14853
b GlaxoSmithKline, Research Triangle Park, NC 27709
cDepartment of Neurology, University of California, San Francisco, CA 94143
dDepartment of Molecular Physiology and Biophysics, Center for Human Genetics Research, Vanderbilt University, Nashville, TN 37232
eUnité Mixte de Recherche 208, Institut de recherche pour le développement (IRD)-Muséum national d’Histoire naturelle (MNHN), Musée de l’Homme, 75116 Paris, France
f Ministére de la Recherche Scientifique et de l’Innovation, BP 1457, Yaoundé, Cameroon
g International Biomedical Research in Africa, Abuja, Nigeria
hDepartments of Genetics and Biology, University of Pennsylvania, Philadelphia, PA 19104
Quantifying patterns of population structure in Africans and African Americans illuminates the history of human populations and is critical for undertaking medical genomic studies on a global scale. To obtain a fine-scale genome-wide perspective of ancestry, we analyze Affymetrix GeneChip 500K genotype data from African Americans (n = 365) and individuals with ancestry from West Africa (n = 203 from 12 populations) and Europe (n = 400 from 42 countries). We find that population structure within the West African sample reflects primarily language and secondarily geographical distance, echoing the Bantu expansion. Among African Americans, analysis of genomic admixture by a principal component-based approach indicates that the median proportion of European ancestry is 18.5% (25th–75th percentiles: 11.6–27.7%), with very large variation among individuals. In the African-American sample as a whole, few autosomal regions showed exceptionally high or low mean African ancestry, but the X chromosome showed elevated levels of African ancestry, consistent with a sex-biased pattern of gene flow with an excess of European male and African female ancestry. We also find that genomic profiles of individual African Americans afford personalized ancestry reconstructions differentiating ancient vs. recent European and African ancestry. Finally, patterns of genetic similarity among inferred African segments of African-American genomes and genomes of contemporary African populations included in this study suggest African ancestry is most similar to non-Bantu Niger-Kordofanian-speaking populations, consistent with historical documents of the African Diaspora and trans-Atlantic slave trade.
