Genetic Polymorphisms And Population Study Of 19 X-STR Loci In Four Ethnic Groups, Northern Guizhou

Objective:（1）To investigate the genetic polymorphism of 19 X-STR loci in Gelao,Tujia,Han and Miao ethnic groups from Northern Guizhou,and provide basic data for the research and application of forensic and genetics in corresponding populations.（2）To evaluate the forensic application value of the 19 X-STR composite detection system in Guizhou Gelao,Tujia,Han and Miao populations.（3）To explore the genetic relationship between four ethnic groups in Northern Guizhou and different regions,ethnic,and language groups in China based on 19 X-STR loci,and to provide reference basis for the research of Chinese population origin,migration and gene fusion.Methods:（1）A total of 1494 unrelated healthy individuals were collected from Guizhou Gelao,Tujia,Han and Miao.（2）Genomic DNA was extracted by salting out method and amplified using the AGCU X19 amplification kit.The amplification products were genotyped by automated genetic analyzer.（3）Allele frequencies,Hardy-Weinberg equilibrium,linkage disequilibrium,heterozygosity,polymorphism information content,power of discrimination and mean paternity exclusion chance were calculated.Haplotype frequencies and forensic parameters,cumulative power of discrimination and cumulative mean paternity exclusion chance based on 7 linkage groups of 19 X-STR loci were calculated.（4）Population comparisons between our studied populations and other 25 populations were further explored through comprehensive population genetic analysis methods based on the frequency of 19 X-STR alleles.Combining the characteristics of history,ethnology and linguistics,the evolution of population origin,migration and integration were employed.Results:（1）All of the 19 X-STR loci of Gelao,Tujia,Han and Miao populations in Northern Guizhou were conform to the Hardy-Weinberg equilibrium.The power of discrimination in males ranged from 0.5434 to 0.9166,0.5206 to 0.9183,0.4832 to 0.9171,0.5213 to 0.9206,respectively.The power of discrimination in females ranged from 0.7030 to 0.9871,0.6897to 0.9875,0.6572 to 0.9872,and 0.6778 to 0.9882,respectively.The mean paternity exclusion chances in duo were 0.8675⁰.9860,0.8783⁰.9863,0.8290⁰.9756,0.8595⁰.9810,respectively.The mean paternity exclusion chances in trio（Desmarais）were 0.9264⁰.9964,0.9327⁰.9931,0.9020⁰.9876,0.9215⁰.9904,respectively.（2）19 X-STRs can be clustered into seven linkage groups.Haplotype frequency distributions of the four groups were between 0.0040⁰.1331,0.0040⁰.1338,0.0040⁰.1765,and 0.0040⁰.1391,respectively.Haplotype diversity ranged from 0.9264to 0.9929,0.9327 to 0.9931,0.9020 to 0.9876,0.9215 to 0.9904,respectively.The power of discrimination in males ranged from 0.9306 to 0.9930,0.9362 to 0.9931,0.9087 to0.9877,0.9262 to 0.9904,respectively.The power of discrimination in females were0.9910⁰.9999,0.9925⁰.9999,0.9850⁰.9997,0.9899⁰.9998,respectively.The cumulative power of discrimination in males in the four ethnic groups were1-2.9051×10-12,1-3.2856×10^-12,1-1.8676×10^-11,1-6.8879×10^-12,and the cumulative power of discrimination in females were 1-8.2079×10^-22,1-9.8315×10^-22,1-3.2112×10^-20,1-4.6216×10^-21,respectively.The cumulative mean paternity exclusion chances in duo were 1-3.1736×10^-10,1-3.5442×10^-10,1-2.3368×10^-9,and 1-7.4986×10^-10,respectively.The cumulative mean paternity exclusion chances in trio were greater than 1-2.5766×10^-9.（3）Population comparisons demonstrated that our studied populations clustered closely and had genetic homogeneity with.the Sintic and Tai-Kadai populations,while were far from the Tibetan populations.Conclusion:（1）Most of the 19 X-STR loci are highly polymorphic in our studied populations,which are of high application value in forensic and population genetics.（2）The seven linkage groups have high polymorphism and information,which can meet the needs of some special cases and complex genetic identification related to X chromosome genetic markers.（3）Population comparisons among 29 Chinese populations are significantly influenced by the geographic position and ethnolinguistic.Our studied populations showed typical geographic clustering characteristics,which may be related to the gene fusion caused by the long-term mixing in history.Except for the Tibetan populations,other populations not only have the uniqueness of the internal relationship in the origin of ethnolinguistic,but also show the characteristic of extensive interaction among multi-groups caused by regional distribution and population migration.