大约5％亲权鉴定案例中无法检测母亲。此类案例的亲权指数(PI)通常必须根据孩子和受指控父亲(AF)的血型来计算。作者指出,尽管此种情况下的正确计算公式很易导出,但令人非常吃惊的是正确的公式显然尚未被广泛了解,而事实上常被使用和引证的是有明显错误的公式。作者首先给出了假定孩子血型为PQ时无论母亲血型是否检测都适用的公式[设Pr(P)=P(?)Pr(Q)=q]:PI=X/Y;其中X=Pr{AF遗传P)×Pr(母亲遗传Q)+Pr{AF遗传 About 5% of paternity test cases can not detect the mother. The parental index (PI) for such cases usually must be calculated on the basis of the blood type of the child and the accused father (AF). The author points out that although the correct formula in this case is easy to derive, it is very surprising that the correct formula has apparently not yet been widely understood, and in fact is often used and cites a formula that has obvious errors. The author first gives a formula that assumes that a child’s blood type is PQ regardless of whether the mother’s blood type is detected or not [let Pr (P) = P (?) Pr (Q) = q]: PI = X / Y; AF genetic P) × Pr (mother’s genetic Q) + Pr {AF genetic