A Joint Test of Transmission Disequilibrium for Quantitative Trait Loci

• Activity Number: 133
• Type: Contributed
• Date/Time: Monday, August 4, 2003 : 12:00 PM to 1:50 PM
• Sponsor: Biometrics Section
• Author(s): Janet K. Holt*+ and Hemant Tiwari and Varghese George and T. Mark Beasley and David B. Allison and Christopher I. Amos
• Companies: Northern Illinois University and University of Alabama and University of Alabama, Birmingham and University of Alabama, Birmingham and University of Alabama, Birmingham and
• Keywords: TDT ; QTL ; OLS regression ; logisitic regression ; extreme sampling ; allele frequency

Abstract

We propose and test a set of statistical models for transmission disequilibrium testing (tests of linkage in the presence of association) for quantitative traits among parent-offspring trios with at least one parent heterozygous at the marker locus. Preliminary simulation studies were conducted for an additive model with the lesser allele frequency of p=.4. Ten thousand replications per condition were simulated to assess Type I error, and 4,000 replications per condition were simulated to assess power. Both full-sample and extreme sampling were conducted. In the extreme sampling condition, the highest 50% of the observations from the phenotypic distribution were sampled. An ordinary least squares (OLS) test with fixed intercept had greatest power of four tests considered in the extreme sampling situation, while OLS regression with a free intercept had the least power. A logistic regression test with fixed intercepts also had good power. Further simulations are under way to test other modes of inheritance and a more extreme allele frequency, conditions under which the logistic approach might be expected to have greatest power.