December 30, 2004

Racial clusters

This study is self-explanatory really, but two interesting findings are the emergence of a "Hispanic" racial cluster, which can be explained by the choice of a population sample from a single location, as Hispanics are generally heterogeneous racially, and the near-perfect differentiation of the Japanese from the Chinese in the Mongoloid cluster, suggesting the potential for subracial differentiation in future studies.

The research also confirms that in terms of genetic similarity, the major split of mankind is between the Mongoloids and the rest, a finding similar to Rosenberg et al. (2002) and to craniometric clustering results.

Am. J. Hum. Genet., 76:000, 2005

Genetic Structure, Self-Identified Race/Ethnicity, and Confounding in Case-Control Association Studies

Hua Tang et al.

We have analyzed genetic data for 326 microsatellite markers that were typed uniformly in a large multiethnic population-based sample of individuals as part of a study of the genetics of hypertension (Family Blood Pressure Program). Subjects identified themselves as belonging to one of four major racial/ethnic groups (white, African American, East Asian, and Hispanic) and were recruited from 15 different geographic locales within the United States and Taiwan. Genetic cluster analysis of the microsatellite markers produced four major clusters, which showed near-perfect correspondence with the four self-reported race/ethnicity categories. Of 3,636 subjects of varying race/ethnicity, only 5 (0.14%) showed genetic cluster membership different from their self-identified race/ethnicity. On the other hand, we detected only modest genetic differentiation between different current geographic locales within each race/ethnicity group. Thus, ancient geographic ancestry, which is highly correlated with self-identified race/ethnicity—as opposed to current residence—is the major determinant of genetic structure in the U.S. population. Implications of this genetic structure for case-control association studies are discussed.


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