Rapidly mutating Y-STRs study in Chinese Yi population

Y-chromosomal short tandem repeats (Y-STRs) have been widely used in forensic analysis and population genetics. With low to moderate mutation rates, conventional Y-STR panels, including commercially available Y-STR kits, enable the identification of male pedigrees but typically fail to differentiate related male individuals. The introduction of rapidly mutating Y-chromosomal short tandem repeats (RM Y-STRs) with higher mutation rates (μ > 10−2) has been demonstrated to increase the discrimination capacity of unrelated men and the differentiation rate of related men compared with standard Y-STRs. To date, several studies have been performed worldwide. Here, 260 father–son pairs from Chinese Yi population were investigated, and 18.8% of them were differentiated with the 13 RM Y-STR markers, which was close to the theoretical estimate of 19.5% based on the mutation rates of these markers. Among the 57 mutations observed, repeat gains were more common than repeat losses (1.48:1), and one-step mutations were more common than two-step mutations (27.5:1). Locus-specific mutation rates ranged from < 3.85 × 10−3 (95% CI 0.00–1.41 × 10−2) to 3.85 × 10−2 (95% CI 1.86 × 10−2–6.96 × 10−2), with an average mutation rate of 1.46 × 10−2 (95% CI 1.11 × 10−2–1.89 × 10−2). Furthermore, we combined the father–son pair data from the present study with the data from the previous studies, generating an overall mutation rate of 1.70 × 10−2. The high differentiation rate obtained in the present study indicates the suitability of RM Y-STRs to distinguish paternal lineages in Chinese Yi population.