Genetic Chaos

Tuesday, June 08, 2004

Genetic relationship of populations in China

Despite the fact that the continuity of morphology of fossil specimens of modern humans found in China has repeatedly challenged the Out-of-Africa hypothesis, Chinese populations are underrepresented in genetic studies. Genetic profiles of 28 populations sampled in China supported the distinction between southern and northern populations, while the latter are biphyletic. Linguistic boundaries are often transgressed across language families studied, reflecting substantial gene flow between populations. Nevertheless, genetic evidence does not support an independent origin of Homo sapiens in China. The phylogeny also suggested that it is more likely that ancestors of the populations currently residing in East Asia entered from Southeast Asia.

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Screening of Y-chromosome STR Loci in Taiwanese Populations

This study examines the diversity of nine Y-chromosome STR in nine aboriginal tribes of Taiwanese. The STR loci were DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385 and DYS388. The populations studied in this survey included Ami, Atayal, Bunun, Paiwan, Puyuma, Rukai, Saisiat, Tsou and Tao tribes. A total of 113 haplotypes for all nine Y-chromosome STR loci were found in 173 unrelated healthy males. The diversity of the nine Y-chromosome STR loci was more variable in Chinese Han population than in nine aboriginal tribes. The minimum diversity for the populations increased significantly with nine Y-STR markers compared to eight markers.

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Polynesian origins: Insights from the Y chromosome

The question surrounding the colonization of Polynesia has remained controversial. Two hypotheses, one postulating Taiwan as the putative homeland and the other asserting a Melanesian origin of the Polynesian people, have received considerable attention. In this work, we present haplotype data based on the distribution of 19 biallelic polymorphisms on the Y chromosome in a sample of 551 male individuals from 36 populations living in Southeast Asia, Taiwan, Micronesia, Melanesia, and Polynesia. Surprisingly, nearly none of the Taiwanese Y haplotypes were found in Micronesia and Polynesia. Likewise, a Melanesian-specific haplotype was not found among the Polynesians. However, all of the Polynesian, Micronesian, and Taiwanese haplotypes are present in the extant Southeast Asian populations. Evidently, the Y-chromosome data do not lend support to either of the prevailing hypotheses. Rather, we postulate that Southeast Asia provided a genetic source for two independent migrations, one toward Taiwan and the other toward Polynesia through island Southeast Asia.

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Analysis of the Alu insertion polymorphism in Taiwanese Han population

We report on a comprehensive study of six Alu insertions within the Taiwanese Han population. Specific primer pairs were designed to amplify and detect the presence (insertion) or absence of human-specific Alu fragments at the loci PLAT, ACE , APO, B65, HS3.23 and HS4.32 in 178 individuals of the Taiwanese Han population and 44 family pairs. The frequencies of Alu insertion were found to be 0.7135 (ACE), 0.5197 (PLAT), 0.9551 (HS3.23), 0.4186 (HS4.32), 0.9354 (APO) and 0.4326 (B65). The discrimination powers ranged from 0.6203 for B65 to 0.1606 for HS3.23 and the combined discrimination power was 0.985. The power of exclusion (PE) for trio case in parentage testing of these six loci ranged from 0.0410 to 0.1873. The joint power of exclusion was approximately 0.5908. The results indicated that the polymorphism of Alu insertion could assist the individual identification and paternity determination in Taiwanese Han population.

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Population study of polymorphic microsatellite DNA in Taiwan

This study examined the population frequency and genetic diversity of 13 autosomal STR loci in 12 populations of Taiwanese. The populations included Bunun, Paiwan, Saisiat, Tao, Ami, Rukai, Atayal, Tsou, Pazeh, Puyumar, Hakka and Han. The STR loci were the CODIS including D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, D16S539, TH01, TPOX and CSF1PO. In this study no deviations from the Hardy-Weinberg equilibrium were observed for the 13 STR loci by the exact test. The range of matching probability for the 13 loci is from 1.44 × 10-13 in Tsou to 8.76 × 10-15 in Taiwanese Han population. Only one mutation event in D8S1179 locus, altering allele 16 to 15, was detected in 250 meiosis alleles in the mutation screening. The Neighbor-joining tree of cluster analysis was constructed with the genetic distance of 12 populations on 13 loci, which may be useful for phylogenetic study of populations in Taiwan. These data supported the Hanization hypothesis for populations in Taiwan.

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