Genetic link between Asians and native Americans: evidence from HLA genes and haplotypes.

We have been studying polymorphisms of HLA class I and II genes in East Asians including Buryat in Siberia, Mongolian, Han Chinese, Man Chinese, Korean Chinese, South Korean, and Taiwan indigenous populations in collaboration with many Asian scientists. Regional populations in Japan, Hondo-Japanese, Ryukyuan, and Ainu, were also studied. HLA-A, -B, and -DRB1 gene frequencies were subjected to the correspondence analysis and calculation of DA distances. The correspondence analysis demonstrated several major clusters of human populations in the world. "Mongoloid" populations were highly diversified, in which several clusters such as Northeast Asians, Southeast Asians, Oceanians, and Native Americans were observed. Interestingly, an indigenous population in North Japan, Ainu, was placed relatively close to Native Americans in the correspondence analysis. Distribution of particular HLA-A, -B, -DRB1 alleles and haplotypes was also analyzed in relation to migration and dispersal routes of ancestral populations. A number of alleles and haplotypes showed characteristic patterns of regional distribution. For example, B39-HR5-DQ7 (B*3901-DRB1*1406-DQB1*0301) was shared by Ainu and Native Americans. A24-Cw8-B48 was commonly observed in Taiwan indigenous populations, Maori in New Zealand, Orochon in Northeast China, Inuit, and Tlingit. These findings further support the genetic link between East Asians and Native Americans. We have proposed that various ancestral populations in East Asia, marked by different HLA haplotypes, had migrated and dispersed through multiple routes. Moreover, relatively small genetic distances and the sharing of several HLA haplotypes between Ainu and Native Americans suggest that these populations are descendants of some Upper Paleolithic populations of East Asia.