Forensic characteristics and genetic variations of Han Chinese population in Shenzhen revealed by 23 autosomal STRs

Autosomal short tandem repeats (STRs) are essential markers for individual identification and paternity testing. To evaluate their forensic utility in the Shenzhen Han population, we genotyped 1,226 unrelated Shenzhen Han individuals using the Huaxia Platinum PCR kit and obtained allele frequencies for 23 autosomal STR loci. We also calculated forensic parameters, assessed linkage disequilibrium (LD) and Hardy-Weinberg equilibrium (HWE), compared population relationships, and characterized mutation patterns.

A total of 1,226 unrelated Shenzhen Han individuals were genotyped at 23 autosomal STR loci using the Huaxia Platinum PCR kit. Allele frequencies and forensic parameters were calculated, and LD and HWE were assessed with Bonferroni correction. Population comparisons were performed using seven Chinese and two non-Chinese populations. Mutation patterns were analyzed in 906 trios and 403 duos from 1,309 paternity cases with a combined paternity index 10,000, comprising 2,514 meioses.

No significant HWE deviations were observed after Bonferroni correction. All loci showed high polymorphism and informativeness, with a cumulative power of exclusion (CPE) of 0.999995664709692. Polymorphism information content (PIC) exceeded 0.70 for all loci except CSF1PO, D3S1358, TH01, and TPOX. PentaE (26 alleles) and FGA (23 alleles) were the most polymorphic loci, whereas TPOX (7 alleles), D13S317 (8 alleles), and D16S539 (8 alleles) were the least polymorphic. Population comparisons revealed close genetic affinity between Shenzhen Han and other Chinese groups, especially Hunan Han. Among 2,514 meioses, 30 mutations were observed across the 23 loci, with locus-specific mutation rates ranging from 0 to 0.159% (D5S818) and an overall rate of 0.085% (95% CI, 0.10-2.87 × 10³).

Our findings confirm that the 23 autosomal STR loci are highly polymorphic and informative in the Shenzhen Han population. These data provide valuable information for forensic and population genetics and support the utility of these loci as a powerful tool for forensic applications.