标准三联体非父排除率计算公式的推导和验证

目的对标准三联体亲子鉴定的非父排除率(PE)进行公式推导和实验验证。方法基于PE定义自行推导公式:PE=sum(P_i~2(1-P_i)~2)from i=1 to n+sum(P_iP_j(1-P_i)~3)from ij to n+sum(P_iP_j(1-P_j)~3)from ij to n+sum(P_iP_j(P_i+P_j)(1-P_i-P_j)~2)from ij to n。将该公式与前人报道的5个公式(1)~(5)进行对比,计算AGCU EX20系统19个常染色体STR基因座的PE值。根据1 000例单亲样本和1 000个无关个体样本设计真实实验,计算PE真实实验值。以随机模拟法产生1 000万对模拟亲母子和1 000万个随机个体,设计模拟实验计算PE模拟实验值。在19个基因座,统计各基因座的等位基因频率之和(S),将PE的公式值、真实实验值和模拟实验值进行对比。结果当S=1时,公式(1)、(2)、(5)、(6)计算结果完全一致,且符合真实和模拟双重实验验证。当S≠1时,公式(1)、(2)、(5)、(6)计算结果有较小误差。公式(3)、(4)的计算结果有较大误差。结论本研究推导的公式(6)与经典公式(1)、(2)、(5)均可用于标准三联体亲子鉴定。S值对PE公式计算有一定影响。

Formula Derivation and Validation of Probability of Exclusion in the Cases of Standard Triplet Parentage Testing

Objective To derive and experiment validate the probability of exclusion (PE) formulas in the cases of standard triplet parentage testing.Methods The formulas were derived voluntarily based on the PE definition:PE=∑Pi2（1-Pi）2+∑PiPj(1-Pi)3+ ∑PiPj（1-Pj）3+∑PiPj（Pi+Pj）(1-Pi-Pj)2.This formula was compared with the 5 formulas (1)-(5) reported previously,and the PE values of 19 autosomal STR loci in AGCU EX20 system were calculated.Based on 1 000 samples of single-parentage cases and 1 000 unrelated individuals,the real experiment was designed and the real experiment results of PE were calculated.Ten million pairs of simulated biological mother and son and 10 million random individuals were gained by random simulation method,and the simulated experiment was designed and the simulated values of PE were calculated.In 19 STR loci,the sum of all allele frequency (S) was calculated,and the formula values of PE were compared with the values of real and simulated experiments.Results If S=I,the calculation values of formula (1),(2),(5) and (6) were quite the same,which accord with the double verification of real and simulated experiments.If S≠ 1,there was a minor error in the calculation results of formula (1),(2),(5) and (6),while which had a large error in formula (3) and (4).Conclusion The formula (6) derived in present study and the classical formulas (1),(2) and (5) can be applied to the standard triplet parentage testing.The S value has a certain influence on PE calculation.