Transmission Disequilibrium Test for quantitative traits based on multiple sibs

Abstract

Background The Transmission Disequilibrium Test (TDT) is a well established family-based test for genetic association. The advantage of TDT over population-based association studies test, which is protected against population stratification, and hence, an association finding can be attributed to the presence of linkage. Quantitative traits (QT) are more informative on within-genotype variability and hence, statistical tests for identifying genes based on such traits tend to be more powerful compared to binary or qualitative traits. The TDT is based on a trio design (two parents and one offspring per family). However, if multiple sibs are present, TDT is only a valid test for linkage. In our study, we have extended the test for quantitative traits based on families with multiple offspring using a logistic regression framework.