Tai-Kadai-speaking Gelao population: Forensic features, genetic diversity and population structure

Genetic analyses of geographically and ethno-linguistically different populations are essential for understanding population stratification and genomic structure in medical Genome-Wide Association Studies (GWAS) and genetic variation and diversity related to forensic and population genetics studies. Here, we genotyped 30 autosomal insertion/deletion (Indel) markers from 502 Tai-Kadai-speaking Gelao individuals residing in the rugged topographical area in Southeastern China. In addition, two comprehensive population genetic comparisons of 15,327 individuals from 95 worldwide populations and of 6122 individuals from Asia and adjoining populations were conducted based on allele frequency data and raw genotype data, respectively. All studied markers were found to be in Hardy-Weinberg equilibrium. The combined power of discrimination in the Gelao minority group was 0.999999999975, and the combined probability of exclusion was 0.9879. Our results from the forensic statistical parameters indicated that this Indel panel can be independently used as a powerful tool in forensic individual identification but can only be used as a complementary tool in paternity cases involving East Asians. We also found significant allele frequency differences between the Gelao and other continental populations with respect to the markers grouped in clusters similar to IV, suggesting that these can be used as forensic ancestry informative Indel markers to distinguish the Gelao from other continental populations. Genetic ancestry analyses demonstrated that Tai-Kadai-speaking Gelao share a dominant ancestry component with Hmong-Mien-speaking Miao. Our population genetic results from multidimensional scaling plots, principal component analysis, neighboring-joining tree construction and hierarchical clustering also suggested that the Zunyi Gelao are genetically closer to their linguistically or geographically close populations, such as the Han Chinese, Guizhou Bouyei and the Hubei Tujia, than to Turkic and Tibeto-Burman speakers.