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Hereditas(Beijing) ›› 2021, Vol. 43 ›› Issue (10): 949-961.doi: 10.16288/j.yczz.21-197

• Research Article • Previous Articles     Next Articles

Actual mutational research of 19 autosomal STRs based on restricted mutation model and big data

Zhiyong Liu2, He Ren3, Chong Chen4, Jingjing Zhang5, Xiaomeng Zhang1, Yan Shi4, Linyu Shi1, Ying Chen4, Feng Cheng1, Li Jia4, Man Chen6, Qingwei Fan7, Jiarong Zhang1, Wanting Li1, Mengchun Wang1, Zilin Ren8, Yacheng Liu4, Ming Ni8, Hongyu Sun2, Jiangwei Yan1()   

  1. 1. School of Forensic Medicine, Shanxi Medical University, Taiyuan 030001, China
    2. Faculty of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
    3. Beijing Police College, Beijing 102202, China
    4. Beijing Tongda Shoucheng Institute of Forensic Science, Beijing 100192, China
    5. Beijing Huayan Judicial Authentication Institute, Beijing 100192, China
    6. School of Forensic Medicine, Southern Medical University, Guangzhou 510515, China
    7. Faculty of Forensic Medicine, North Sichuan Medical College, Nanchong 637000, China
    8. Beijing Institute of Radiation Medicine, Beijing 100850, China
  • Received:2021-06-02 Revised:2021-08-18 Online:2021-10-20 Published:2021-08-31
  • Contact: Yan Jiangwei E-mail:yanjw@sxmu.edu.cn
  • Supported by:
    Supported by the National Natural Science Foundation of China No(82030058)

Abstract:

Short tandem repeat (STR) markers have been widely used in forensic paternity testing and individual identification, but the STR mutation might impact on the forensic result interpretation. Importantly, the STR mutation rate was underestimated due to ignoring the “hidden” mutation phenomenon in most similar studies. Considering this, we use Slooten and Ricciardi’s restricted mutation model based on big data to obtain more accurate mutation rates for each marker. In this paper, the mutations of 20 autosomal STRs loci (D3S1358, D1S1656, D13S317, Penta E, D16S539, D18S51, D2S1338, CSF1PO, Penta D, TH01, vWA, D21S11, D6S1043, D7S820, D5S818, TPOX, D8S1179, D12S391, D19S433, and FGA; The restricted model does not include the correction factor of D6S1043, this paper calculates remaining 19 STR loci mutation rates) were investigated in 28,313 (Total: 78,739 individuals) confirmed parentage-testing cases in Chinese Han population. As a result, total 1665 mutations were found in all loci, including 1614 one-steps, 34 two-steps, 8 three-steps, and 9 nonintegral mutations. The loci-specific average mutation rates ranged from 0.00007700 (TPOX) to 0.00459050 (FGA) in trio’s and 0.00000000 (TPOX) to 0.00344850 (FGA) in duo’s. We analyzed the relationship between mutation rates of the apparent and actual, the trio’s and duo’s, the paternal and maternal, respectively. The results demonstrated that the actual mutation rates are more than the apparent mostly, and the values of μ1”/μ2”(apparent) are also greater than μ1/μ2 (actual) commonly (μ1”, μ1; μ2”, μ2 are the mutation rates of one-step and two-step). Therefore, the “hidden” mutations are identified. In addition, the mutations rates of trio’s and duo’s, the paternal and maternal, exhibit significant difference. Next, those mutation data are used to do a comparison with the studies of other Han populations in China, which present the temporal and regional disparities. Due to the large sample size, some rare mutation events, such as monozygotic (MZ) mutation and “fake four-step mutation”, are also reported in this study. In conclusion, the estimation values of actual mutations are obtained based on big data, they can not only provide basic data for the Chinese forensic DNA and population genetics databases, but also have important significance for the development of forensic individual identification, paternity testing and genetics research.

Key words: autosomal STR, restricted mutation model, parentage testing, Chinese Han population, mutational analysis