Abstract: Objective To investigate the genetic data of the 19 X-STR loci in three ethnicities of China ( Han，Gelao，Miao) and to assess the application value in forensic science. Methods The DNA samples of unrelated individual in Han ( n = 308)，Gelao ( n = 398)，Miao ( n = 323) populations were amplified using Microreader? 19X ID System kit, and the PCR products were analyzed by electrophoresis through 3500XL genetic analyzer. The fragment sizes of alleles were taken subsequently by GeneMapper? ID-X.Allele frequencies and population genetics parameters of the 19 X-STR were analyzed by statistics. The allele frequencies were compared among the three nationalities and were compared with available data of other Han populations from different regions. Results After the Bonferroni correction at a 95% significance level (p=0.0026), no significant departures from the Hardy–Weinberg equilibrium were observed. Linkage disequilibrium test showed no significant allelic association between all 19 X-STR loci after Bonferroni’s correction. The cumulative discrimination power in females and in males were greater than 0.999 999 999 99 and 0.999 999 999 94,respectively. The combined power of exclusion in trios and in duos were greater than 0.999 999 999 36 and 0.999 999 52,respectively. The p values,calculated throuth Arlequin v3.5 software,there were statistically significant differences detected at loci of X-STR among the different nationalities. Conclusions This panel of X-STR is highly polymorphic in three Chinese populations and can be served as a supplementary to the current STR system for individual identification.

Key words: forensic genetics, X-chromosomal short tandem repeats (X-STR), polymorphism,genetic, Han,Gelao,Miao, China