Str Polymorphisms Of Henan Population And The Study On Central Plains Han Origin Of Chaoshanese

Background: Short tandem repeat (STR), also called microsatellite, is length polymorphism sequence with a tandem repeats of 2-6bp in length as its repeat unit, which widely exist in the human genome. The STR is abundant with one in every 20Kb on average in the human genome. The difference of repeat unit and variability of the repeat number construct its length polymorphism. Progress of study on STR as genetic markers has led to its application to trace the human origin, migration and evolution at the genetic level. Chaoshan, the eastern part of Guangdong Province, is a littoral located at the southeast of the Mainland China with its east abutting on Fujian. The whole region covers the areas of Shantou, Chaozhou, and Jieyang. People residing in this area speak in a unique dialect and have distinct lifestyle and are defined as Chaoshanese. According to history records, the modern Chaoshanese originated from ancient Central Plains Han. Our previous study based on Human leucocyte antigen (HLA) intended to test the hypothesis that Chaoshanese derive from the Central Plain Han, and has yet provided genetic evidence for the hypothesis.Objective: To study the genetic polymorphism of Henan populaton and trace the hypothesis of Central Plains Han origin of Chaoshanese at the STR level.Method: Using a combined method of fluorescence labeled PCR and capillary electrophoresis, we studied the genetic polymorphism of 15 STR loci in 200 unrelated healthy individuals in Henan Han population and Penta D, Penta E STR loci in three Chinese populations (Chaoshan, Henan, Minnan). Combining our published STR allele frequency data and some new samples added (data not yet published) in Chaoshan population and STR data of other populations in different area which obtained from peer-reviewed journals, using the PHYLIP software, we calculated the Nei's genetic distance D'between the populations. The neighbor-joining phylogenetic tree was constructed based on the obtained Nei's genetic distance to reveal population affinities and the Central Plains Han origin of Chaoshanese. Result: For 15 STR loci in Henan population, a total of 142 alleles and 451 genotypes were detected, for Penta D and Penta E STR loci in Chaoshan, Henan, Minnan population, the number of alleles and genotypes detected was 27 and 116,28 and 117,26 and 95 respectively. No deviation from Hardy-Weinberg equilibrium was observed (a 5% significance level is taken) for 17 STR loci except for D3S1358 (P=0.04) in Henan population. The phylogenic tree based on CODIS STR allele frequencies showed that Chaoshan Han was much closer to Minnan Han, and relatively closer to Henan Han. Admixture analysis indicated that Chaoshan Han and Minnan Han have similar proportional contributions from the Central Plains Han and the proportion was greater than 60%. Distinction between north and south population in China was noticeable in the phylogenic tree.Conclusion: The 15 STR loci studied have potential usefulness for paternity testing and forensic casework in Henan population. The genetic polymorphism of Penta D and Penta E STR loci is high, and can be used as alternative loci in the construction of DNA database in our country. Our study showed that the genetic similarity sustained by Chaoshan Han and Minnan Han, and a strong Central Plains Han parental influence on the two groups gene pool. There is significant genetic difference between Southern and Northern populations in China.