Y chromosomal DNA variation in East Asian populations and its potential for inferring the peopling of Korea

We have examined variations of five polymorphic loci (DYTS287, DXYS5Y, SRY4 65, DYS19, and DXYS156Y) on the Y chromosome in samples from a total of 126 0 males in eight ethnic groups of East Asia. We found four unique haplotype s constructed from three biallelic markers in these samples of East Asians. The Japanese population was characterized by a relatively high frequency o f either the haplotype I-2b (-/Y2/T) or II-I (+/Y1/C). These dual patterns of the distribution of Y chromosomes (I-2b/II-1) were also found in Korea, although they were present at relatively low frequencies. The haplotype II- 1 was present in Northeast Asian populations (Chinese, Japanese, Koreans, a nd Mongolians) only, except for one male from the Thai population among the Southeast Asian populations (Indonesians, Philippines, Thais, and Vietname se). The Japanese were revealed to have the highest frequency of this haplo type (27.5%), followed by Koreans (2.9%), Mongolians (2.6%), and mainland C hinese (2.2%). In contrast, the frequency of the haplotype I-2b was found t o be 17.1% in the Japanese, 9.5% in Indonesian, 6.3% in Korean, 3.8% in Vie tnamese, and 2.7% in Thai samples. These findings suggested that the chromo somes of haplotype I-2b were likely derived from certain areas of Northeast Asia, the region closest to Southeast Asia. Phylogenetic analysis using th e neighbor-joining tree also reflected a general distinction between Southe ast and Northeast Asian populations. The phylogeny revealed a closer geneti c relationship between Japanese and Koreans than to the other surveyed Asia n populations. Based on the result of the dual patterns of the haplotype di stribution, it is more likely that the population structure of Koreans may not have evolved from a single ancient population derived from Northeast As ians, but through dual infusions of Y chromosomes entering Korea from two d ifferent waves of East Asians.