Population genetics, diversity and forensic characteristics of Tai–Kadai-speaking Bouyei revealed by insertion/deletions markers

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.