F_ST estimates of 94 populations in China based on STR markers

The proper assessment of DNA evidence in cases of personal identification is a recurring theme in forensics. It is common practice to evaluate the strength of DNA evidence using the likelihood ratio (LR). The accurate use of population allele frequencies is a crucial problem in LR calculation. Allele frequency differences among different populations could be estimated by the F_ST values. Thus, F_ST would also affect LR values by correcting the allele frequencies. In this study, Chinese population allele frequency data were selected from population reports published in Chinese and English journals. The population-specific F_ST values of each population, the overall F_ST values of each province, each region, and the whole country, and the locus-specific F_ST values of different loci were calculated. The LRs using different allele frequencies and different F_ST values were compared based on the combination of simulated genotypes. As a result, the F_ST values of 94 populations, 19 provinces, 7 regions, and the whole country were obtained. The LR was overestimated using allele frequencies of the combined population containing multiple populations rather than using allele frequencies of a population, and the LRs after F_ST correction were lower than those without correction. Conclusively, the correction in conjunction with corresponding F_ST values can make the LRs more accurate and reasonable.