MacLean C J, Bishop D T, Sherman S L, Diehl S R
Department of Psychiatry, Medical College of Virginia/Virginia Commonwealth University, Richmond 23298.
Am J Hum Genet. 1993 Feb;52(2):354-61.
We consider probability distributions of alternative lod statistics, differing in their treatment of segregation parameters when mode of inheritance is uncertain. A particular pedigree structure and a dominant genetic system displaying incomplete penetrance are analyzed. Lod scores calculated assuming an incorrect segregation model appear to conform quite well to the chi 2 distribution in the absence of linkage. In the presence of linkage, some power is lost. However, if lod scores are calculated under several different segregation models and the best one is accepted, opportunity for chance occurrence of high lod scores is enhanced. The distribution is still chi 2, but with extra degrees of freedom. These results hold over a wide range of sample sizes and segregation models, including small samples and low levels of penetrance.
我们考虑了在遗传模式不确定时，对分离参数处理方式不同的替代对数优势比统计量的概率分布。分析了一种特定的家系结构和一个显示不完全外显率的显性遗传系统。在不存在连锁的情况下，假设错误的分离模型计算出的对数优势比分数似乎与卡方分布相当吻合。在存在连锁的情况下，会损失一些检验效能。然而，如果在几种不同的分离模型下计算对数优势比分数并接受最佳模型，那么出现高对数优势比分数的偶然机会就会增加。分布仍然是卡方分布，但有额外的自由度。这些结果在广泛的样本量和分离模型范围内都成立，包括小样本和低外显率水平。
