Abstract: Objective To investigate the genetic polymorphism of 21 autosomal STR loci and DYS391 locus of SiFaSTRTM 23plex DNA ID system in Han population of eastern China and to evaluate its application value in forensic science. Methods Typing test of 2 000 unrelated individuals was performed using SiFaSTRTM 23plex DNA ID system. The population genetic parameters of STR loci were statistically analysed. A total of 3 198 parentage confirmed cases were detected with that system and the mutation conditions were observed in 21 autosomal STR loci. Results All the 21 autosomal STR loci showed no significant departure from Hardy-Weinberg equilibrium （P>0.05）. The Ho ranged from 0.617 5 to 0.927 0. The DP ranged from 0.796 4 to 0.986 9, as well as the PIC distributed from 0.561 1 to 0.912 3. The CDP was 0.999 999 999 999 999. The CPEduo was 0.999 997 431 701 961, while CPEtrio was 0.999 999 999 654 865. Five alleles were detected in DYS391 locus, with the allele frequency from 0.004 0 to 0.729 0, and GD was 0.418 9. Except D13S317 and D10S1248, seventy-six mutation events were observed at the rest nineteen autosomal STR loci. Among them, seventy-five （98.68%） were one step mutation, and only one （1.32%） was three steps mutation. The mutation rate ranged from 0.246 5×10-3 to 2.711 4×10-3, and the averaged mutation rate was 0.892 1×10-3 （95% CI： 0.70×10-3-1.10×10-3）. In 33 trio mutation cases, the proportion of the paternal mutation and the maternal mutation was 2.09∶1. Conclusion The involved STRs are highly polymorphic in Eastern Han population with acceptable mutation rates by the SiFaSTRTM 23plex DNA ID system, which is suitable for paternity testing and individual identification.

Key words: forensic genetics, polymorphism, genetic, DNA mutational analysis, short tandem repeat, Han nationality, Eastern China