The power of transmission disequilibrium tests for quantitative traits

We develop a score statistic to test for linkage in the presence of linkage disequilibrium for quantitative traits. We then extend this method to anal yze multiple tightly linked markers. One potential limitation with the use of many genetic markers is the large number of degrees of freedom involved that may reduce the overall power to detect linkage. To overcome this limit ation, we propose to group haplotypes on the basis of haplotype similarity before performing transmission disequilibrium tests. Finally, we apply thes e methods to the Genetic Analysis Workshop 12 simulated data and compare th eir power. (C) 2001 Wiley-Liss, Inc.