Objective To study the genetic relationship of the Y chromosomal short tandem repeat gene loci in Lanzhou Han population and other 25 populations .Methods The frequency of alleles of Y-STRloci was obtained from a sample of 500 unrelated individuals living in Lanzhou City , and other 25 populations in different areas collected from the published data were used to calculate the genetic similarity coefficient and genetic distance .Phylogenetic trees based on the genetic distance were established .Results Populations of Lanzhou , Beijing, Shanxi and Inner Mongolia were in an identical cluster .Compared with minorities , the genetic distance between Lanzhou Han population and Inner Mongolia Mongolian population was dramatically smaller from other subpopulations .The populations in Malays and Indians were far from the other groups .Conclusion The Y-STR gene frequency distribution in 26 populations has identified differentiation in race, clime and evolution, and it is basically identical with the classification of human races which is similar to or according with other molecular anthropology research conclusions .

Objective To determine the genetic polymorphism of 24 Y-STR loci haplotype and investigate its application value in legal physical evidence.Methods AGCU Y24 kit and 3130xl Genetic Analyzer were used to detect the distribution of 24 Y-STR loci including DYS391,DYS389Ⅰ,DYS439,DYS389Ⅱ, DYS438, DYS643, DYS456, DYS458, DYS437, DYS635, DYS448, DYS527a/b, Y-GATA-H4, DYS447, DYS19,DYS392,DYS522,DYS393,DYS388,DYS390,DYS385a/b and DYS444in 154 unrelated individuals of Dongxiang ethnic minority males in Gansu province of China.Results A total number of 153 haplo-types were detected in 154 samples, the haplotype diversity was 0.9915 and the discrimination power was 0.9940.Conclusion The 24 Y-STR loci system has high haplotype diversity and discrimination power.

Objective To com pare the concentration of teeth DNA extracted by three different pretreatm ent m ethods and to explore a sim ple, econom ical and practical pretreatm ent m ethod w ith high concentration of extracted DNA from teeth. Methods A total num ber of 21 m olars w ere collected from 7 corpses. The pretreatm ent of 3 m olars from each individual w as random ly perform ed by tooth crum b m ethod, ball-m illing m ethod and liquid nitrogen m illing m ethod and 50 m g tooth crum b w as w eight and DNA w as extracted by A utoM ate ExpressTM forensic DNA extraction system . Subsequently, the concentration of DNA and corresponding STR genotyping of three m ethods w ere com pared. Results The DNA concentration extracted by tooth crum b m ethod, ball-m illing m ethod and liquid nitrogen m illing m ethod w as 0.055 6-1.989 1 ng/μL , 0.036 6-1.175 6 ng/μL and 0.037 8-1.249 0 ng/μL , respectively. The DNA concentration ob-tained by tooth crum b m ethod w as higher (P<0.05) and the success rate of STR genotyping w as high. Conclusion C om bined w ith A utoM ate ExpressTM forensic DNA extraction system , tooth crum b m ethod is an efficient and feasible m ethod to extract DNA from teeth, w hich can be applied in forensic practice.