Mutation analysis of 21 autosomal short tandem repeats in Han population from Hunan, China

<b>Background:</b> Short tandem repeats (STRs) are powerful genetic markers widely used in human genetics. Population data and locus-specific mutation rates of STRs are crucial for the evaluation and interpretation of genetic evidence in forensic and population genetics. <b>Aim:</b> To investigate the mutation rates of 21 autosomal STRs in a population from central south China. <b>Subjects and methods:</b> This study analysed 3420 paternity cases with a Combined Paternity Index &gt;10,000 from Han population in Hunan. A total of 68,743 meiotic transfers were analysed and 62 mutations were identified. <b>Results:</b> The overall mutation rate of STR loci was 0.9 × 10⁻³ (95% CI, 0.0007–0.0011) and the locus-specific mutation rates were estimated ranging from 0.0000–0.0023. Locus D1S1656 exhibited the highest mutation rate of 2.3 × 10⁻³ (95% CI, 0.0005–0.0006), followed by D12S391 with a mutation rate of 2.0 × 10⁻³ (95% CI, 0.0007–0.0044). No mutation was observed at TPOX, D2S1338 or Penta D. One-step mutation cases accounted for 96.77% of total mutations and the ratio of paternal vs maternal mutations was ∼4.85:1. Inter-population comparisons of locus-specific mutation rates of several STRs revealed significant differences between Han in Hunan and Han in other regions of China. <b>Conclusion:</b> The data justified the use of geographical data in further genetic applications.