基于高通量测序的SNP计算无创产前亲子鉴定的方法

Method for non-invasive prenatal paternity testing based on SNP calculation through high-throughput sequencing

目的推导产前亲子鉴定(NIPPT)的亲权指数(PI)和排除概率(PE)公式,并对PE公式进行实验验证,以及对PI公式进行统计分析。方法首先,将NIPPT分为产前亲母疑父鉴定(PAF)、产前低度亲母疑父鉴定(PLAF)、产前父子鉴定(PFC)、产前母子鉴定(PMC)、产前双亲皆疑鉴定(PAP)和产前亲父疑母鉴定(PAM)共6类;其次,分别推导符合遗传规律情形和突变情形下的6类鉴定的PI公式,以及对应的PE公式,并依据10个SNP的数据计算PE的公式值,设计模拟实验在同样的SNP上计算出PE的模拟值,将模拟值对比公式值,对所推导公式进行实验验证;最后,在100个SNP系统上,分别建立模拟亲缘组和无关个体组模型,统计累积亲权指数(CPI)的几何平均数(Π)、95%置信区间(CI)、亲缘组中CPI>10~4的百分比和无关个体组中CPI<10-4的百分比。结果本文推导的PE公式经实验验证与之符合。本文推导的所有情形下的PI公式,任意分型组合均可计算对应的PI。在100个SNP系统上,所有鉴定的亲缘组和无关个体组均可获得明确结论;PLAF在50个SNP系统上,75.90%的亲缘组和100%的无关个体组可获得明确结论。结论本文公式可应用于NIPPT的PI和PE计算,具有法医学应用价值。

Objective To derive the parentage index(PI)and power of exclusion(PE)formulars for non-invasive prenatal paternity testing(NIPPT),empirically validate the PE formula,and conduct statistical analysis on the PI formula.Methods Firstly,NIPPT was divided into 6 types,including Prenatal parentage testing of Alleged Father with biological mother(PAF),prenatal parentage testing of low fetal concentration Alleged Father with biological mother(PLAF),Prenatal parentage testing of Father-Child(PFC),Prenatal parentage testing of Mother-Child(PMC),Prenatal parentage testing of Alleged Parents(PAP),Prenatal parentage testing of Alleged mother with biological father(PAM).Then the formulas of PI in 6 types of NIPPT both in accordance with genetic laws and in the presence of mutation were derived.The calculation formulas of PE were mathematically derived and applied to the system of 10 SNP loci.And for the same 10 SNP sites,PE was simulated and measured through multiple groups of operation.In principle,the PE formula should be empirically verified using the correlation method for the corresponding values of the formula and simulation.Finally,models of simulated kinship groups and unrelated individual groups were established respectively with 30 to 100 SNP loci.The geometric mean(Π)and 95%confidence interval(CI)of cumulative parentage index(CPI),the percentages of cases where CPI>10^(4)in kinship groups,and the percentages of cases where CPI<10-4 in unrelated individual groups were calculated.Results The formula of PE was all in accord with the simulation experiments.The novel formulas can be used to calculate all kinds of PI in all situations.All types of NIPPT cases in kinship group and unrelated individual group can be correctly identified with 100 SNP loci.In PLAF,75.90%cases in kinship group and 100%cases in unrelated individual group can be correctly identified in 50 SNP loci.Conclusion The formula in this paper can be applied to the calculation of PI and PE of NIPPT and has forensic application value.