基于选择基因型对数量性状进行关联分析

数量性状的遗传分析可以通过＂选择基因型＂的方式完成。本文提出了一个利用极端样本来对数量性状位点（QTL）进行关联分析的统计量T。统计量T比较上极端群体样本中具有纯合子标记的性状值差异。通过计算机模拟考察了无关联情形时T的分布和Ⅰ型错误率,结果表明,在各种样本选择策略下,T的分布近似于χ^2-分布,Ⅰ型错误率接近设定的显著性水平。同时,考察了各种遗传模型下不同遗传率,不同样本大小,及不同样本选择阈值对T的统计功效的影响,结果表明,T的功效随着标记和QTL间连锁不平衡程度的增强及遗传率和样本大小的增大而增大,当样本选择阈值更严格时,功效也越大。

Association Study of a QTL by Selective Genotyping

Genetic studies of quantitative traits can be accomplished through the method of selective genotyping.In this article,we proposed a statistic T for association analysis of a quantitative trait locus（QTL） by selective genotyping.The statistic T is to compare the difference between the mean trait values for homozygotes of the marker in the upper extreme sample.To evaluate the statistical properties of the statistic T ,its distribution and typeⅠerror rate were examined under the null hypothesis of no association by simulation.Simulation results showed that the distributions of T were similar to the theoretical central χ^2distributions and the typeⅠerror rates were around the nominal significance levels for various sample-selection strategies.The power of the statistic T was investigated under various heritability,various sample sizes,and various percentiles selected for three genetic models.The results showed that the power always increases with increasing linkage disequilibrium（LD） between the marker and the trait locus.As expected,power increases when sample size and heritability increase,and also increases with more-stringent selective-genotyping procedures.