Mutability analysis towards 21 STR loci included in the AGCU 21 + 1 kit in Chinese Han population

To further illustrate the mutation traits of 21 autosomal STR loci involved in the newly developed AGCU 21 + 1 kit, randomly selected 485 trios were focused on. We have previously confirmed the biological father-mother-child relationships of these trios. Then matters of mutation rates, steps, and origins of the 21 STR loci were statically analyzed. Results showed 35 mutation events occurred at 16 STR loci of the panel during 20,370 meiosis, and the locus-specific mutation rates ranged from 0.000 to 1.134% (D3S4529), with an overall mutation rate of 1.72 × 10^-3 (95%CI, 1.20-2.39 × 10^-3). Mutation origins exhibited slight discrepancy between male and female germlines, 18 of the 35 mutation events were verified to be contributed by fathers and 13 by mothers, with origins of the remaining 4 events hardly to be assigned. Furthermore, 77.14% of the mutations were one-step mutation. Currently, portraits on mutability of the STR loci involved in the AGCU 21 + 1 panel were barely reported. In view of this, we conclude our data will enrich the mutation information of the 21 STR loci and provide valuable suggestions in calculating likelihood ratios for mutation-involved parental testing cases.