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Background: Guizhou province is located in southwest China with abundant genetic, linguistic and cultural diversity. The Bouyei is one of the 18 officially recognised minority groups in Guizhou, accounting for about 97% of the total Bouyei population in China. However, the genetic history and forensic characterisation of the Bouyei people is largely unknown due to a lack of genetic data. Aim: We aim to investigate genetic polymorphisms and forensic characterisation of the Guizhou Bouyei population, as well as the relationships between the Bouyei and other East Asian populations. Subjects and methods: We genotyped 19 X-STRs in 188 males and 165 females of Guizhou Bouyei using the AGCU X19 STR Kit. We estimated allele frequencies, forensic parameters and genetic distances between the Bouyei and other East Asian populations. We presented the genetic distances in a phylogenetic tree, an MDS plot and a PCA plot. Results: In Guizhou Bouyei individuals, we observed 216 alleles with corresponding frequencies ranging from 0.0019 to 0.6757. All of the six combined powers of PDm, PDf, MEC Krüger, MEC Kishida, MEC Desmarais and MEC Desmarais in allele diversity and haplotype diversity are larger than 0.99999995. We found genetic affinities among the Bouyei people and their geographical neighbouring populations in Guizhou, such as the Sui, Miao and Han. Conclusions: The highly polymorphic and informative forensic parameters of the 19 X-STRs in Bouyei people show the powerful potential of those markers in forensic identification and parentage tests. The genetic relationships of the Bouyei with other East Asian populations correspond well with geographic affiliations as well as linguistic classifications.

China, inhabited by over 1.3 billion people and known for its genetic, cultural and linguistic diversity, is considered to be indispensable for understanding the association between language families and genetic diversity. In order to get a better understanding of the genetic diversity and forensic characteristics of Tai-Kadai-speaking populations in Southwest China, we genotyped 30 insertion/deletion (InDel) markers and amelogenin in 205 individuals from Tai-Kadai-speaking Bouyei people using the Qiagen Investigator DIPplex amplification kit. We carried out a comprehensive population genetic relationship investigation among 14,303 individuals from 84 worldwide populations based on allele frequency correlation and 4907 genotypes of 30 InDels from 36 populations distributed in all continental or major subregions and seven linguistic phyla in China. Forensic parameters observed show highly polymorphic and informative features for Asians, although the DIPplex kit was developed focusing on Europeans, and indicate that this amplification system is appropriate to forensic personal identification and parentage testing. Patterns of InDel variations revealed by principal components analysis, multidimensional scaling plots, phylogenetic relationship exploration, model-based clustering as well as four pairwise genetic distances (Fst, Nei, Cavalli-Sforza and Reynolds) demonstrate significant genetic differentiation at the continental scale and genetic uniformity in Asia except for Tibeto-Burman and Turkic-speaking populations. Additionally, Tai-Kadai speakers, including Bouyei, Zhuang and Dong, share more genetic ancestry components than with other language speakers, and in general they are genetically very similar to Hmong-Mien-speaking populations. The dataset of Bouyei people generated in the present study is valuable for forensic identification and parentage tests in China.

Background: Guizhou Sui people are an officially recognised ethnic group living in southwest China, but have seldom been studied genetically. Aim: To investigate the polymorphisms of 19 X-chromosome STR loci in a typical Sui population and enrich the East Asian X-STR reference database for forensic DNA analysis. Subjects and methods: A total of 400 Sui individuals (195 males and 205 females) were genotyped at 19 X-STR loci using the AGCU X19 STR Kit. The allele frequencies and forensic parameters were calculated and illustrated and the data of Guizhou Sui were merged with 18 other nationwide populations to explore genetic polymorphisms and population relationships. Results: A total of 215 alleles were observed with corresponding frequencies ranging from 0.0017–0.6512 in Sui using male and female pooled allele frequencies. Large values were observed, at least 0.9999999933, in combined powers of discrimination of Sui males and females, as well as the four mean paternity exclusion chances (MECs). The phylogenetic analysis among 19 populations showed that Sui have close genetic affinities with other Tai-Kadai populations, as well as the Sinitic populations living in southern China. Conclusions: The AGCU X-19 STRs are highly polymorphic and informative in Guizhou Sui people. The genetic relationships between Sui and other populations in China are generally consistent with the language classification and geographical distance.