Donnelly P
School of Mathematical Sciences, Queen Mary and Westfield College, London, U.K.
Heredity (Edinb). 1995 Jul;75 ( Pt 1):26-34. doi: 10.1038/hdy.1995.100.
In comparing a particular DNA profile with that from an unknown (but distinct) individual, matches at different loci between the profiles will not be independent, even in a randomly mating population, because of the presence in the population of relatives of the individuals. The paper contains a theoretical analysis of the extent of this effect on the match probability, for profiling techniques which separately probe different loci. Naive calculation using the product rule could substantially understate the match probability. Past a certain point, the testing of additional loci provides no more information than would be available in discriminating between sibs. The correlation effect described here would be unimportant in criminal casework if close relatives of the suspect, and in particular full-sibs, were excluded as possible culprits. In the absence of such exclusions the current practice of effectively ignoring such relatives in presenting match probabilities could be extremely prejudicial to a suspect, even in cases in which there is no direct evidence to incriminate his/her relatives.
在将特定的DNA图谱与来自未知（但不同）个体的图谱进行比较时，即使在随机交配的群体中，由于群体中个体存在亲属关系，图谱在不同基因座上的匹配也不会是独立的。本文对这种效应在匹配概率上的影响程度进行了理论分析，针对的是分别探测不同基因座的图谱分析技术。使用乘积法则进行的简单计算可能会大幅低估匹配概率。超过某一点后，对额外基因座的检测所提供的信息并不比区分同胞时所能获得的信息更多。如果嫌疑人的近亲，特别是同胞，被排除在可能的罪犯之外，那么这里描述的相关效应在刑事调查中就不重要。在没有这种排除的情况下，目前在呈现匹配概率时有效忽略此类亲属的做法可能会对嫌疑人极为不利，即使在没有直接证据指控其亲属的案件中也是如此。
