Fig. 1.

PCA of genetic ancestry in Chinese populations using genome-wide SNP data. (A) Result from a PCA in a combined sample of 3,381 genetically confirmed Tibetan and Han from this study and 180 Chinese subjects (multiple ethnic groups) from the HGDP. PC1 and PC2 represent the first two eigenvectors from PCA. Note that one of the Yi subjects from the HGDP seems to be of Tibetan ancestry. (B) Distribution of the ethnic groups in China. The blue circles represent the main distribution areas of the ethnic populations in the HGDP, and the red circle represents the Tibetan population. Note that many of the populations, such as Han, Mongola, Tibetan, and Uygur, are distributed widely in a range of regions rather than the specific areas labeled on the map. The green triangles represent the two areas (Seda and Litang) from which our Tibetan subjects were recruited (SI Appendix, Fig. S1).