Abstract: Objective To investigate the genetic polymorphisms of 27 Y-STR in Dongxiang population of Gansu province, and to explore the population genetic relationship and the value of forensic application. Methods The genotyping of 27 Y-STR loci in 526 unrelated male individuals in Dongxiang population of Gansu province were detected by STRtyper-27Y kit. The allele frequencies and haplotype diversity were also calculated. Combining with other genetics data of 14 loci in same populations, which have been published at home and abroad, the genetic distance and clustering relationship in Dongxiang population of Gansu province were calculated. Results Totally 55 haplotypes were found in the DYS385a/b biallelic loci, 39 haplotypes in DYF387S1 loci, and 4-16 alleles in the rest 23 single copy STR loci. The GD value was from 0.453 9 （DYS391） to 0.957 5 （DYS385a/b）. Totally 471 haplotypes were observed in 27 Y-STR loci in 526 individuals, and the value of haplotypes diversity was 0.999 5. The genetic distance between Dongxiang and Tibetan populations of Gansu province was the closest （0.068 2）, while it was the longest between Dongxiang population in Gansu province and Han population in Henan province （0.084 7）. The result of dimensional analysis established upon the genetic distance was basically matched with that of the cluster analysis. Conclusion The 27 Y-STR loci show a high genetic polymorphism in Dongxiang population of Gansu province, which has significance for the Y-STR database establishment, population genetics study and forensic practice.

Key words: forensic genetics, polymorphism, genetic, tandem repeat sequences, Y chromosome, Gansu, Dongxiang nationality