X-chromosomal STRs for genetic composition analysis of Guizhou Dong group and its phylogenetic relationships with other reference populations.

BACKGROUND X-chromosomes show a specific genetic mode, which makes genetic markers on the X chromosome play crucial roles in forensic research and human evolution. Dong group, one of 55 minority groups in China, live in Guizhou, Guangxi and Hunan provinces. Even though some genetic data of Y chromosomal short tandem repeats (STRs) and autosomal insertion/deletion polymorphism (InDels) in Dong groups have been reported, there is little research about X-STRs in the Dong group. AIM Purposes of this study are to investigate allelic distributions and forensic statistical parameters of 19 X-STRs in the Guizhou Dong group, and explore the genetic composition of the Guizhou Dong group and its phylogenetic relationships with other reference populations. SUBJECTS AND METHODS 507 Dongs (272 males and 235 females) living in Guizhou province were typed using the AGCU X19 STR kit. Allelic frequencies and forensic parameters of 19 X-STRs in the Guizhou Dong group were calculated. Population genetic analyses of Guizhou Dong and other 17 reference populations were conducted using DA genetic distances, phylogenetic tree, principal component analysis and multidimensional scaling. RESULTS A total of 230 alleles of 19 X-STRs were identified in all Dongs. The frequencies of 19 loci ranged from 0.0013 to 0.6838. Cumulative power of discrimination in males (PDM), Cumulative power of discrimination in females (PDF), four different kinds of mean exclusion chance (MEC_Kruger, MEC_Kishida, MEC_Desmarais and MEC_Desmarais_du) values of 19 X-STRs in all individuals were 0.999999999999761, 0.9999999999999999999993951, 0.999999964841617, 0.999999999997261, 0.999999999997297 and 0.999999993623172, respectively. Besides, genetic polymorphisms of seven linkage clusters ranged from 0.9381 to 0.9963. In addition, these seven groups showed high polymorphism information content (PIC), PDM, PDF, MEC_Kruger, MEC_Kishida, MEC_Desmarais and MEC_Desmarais_duo values. Population genetic analyses of Guizhou Dong and other 17 reference populations showed that the Guizhou Dong group had close genetic relationships with surrounding Tai-Kadai-speaking, Hmong-Mien-speaking and Han groups. CONCLUSION Nineteen X-STRs displayed high genetic diversities and could be employed for forensic personal identification and paternity analysis in the Guizhou Dong group. Close genetic affinities between Guizhou Dong and surrounding populations were observed based on the 19 X-STRs in 17 reference populations.