title: Increase in power of transmission-disequilibrium tests for quantitative traits.
abstract: Allison ([1997] Am. J. Hum. Genet. 60:676-690) proposed four versions of the transmission-disequilibrium test (TDT) for quantitative traits when there is extreme-threshold sampling, i.e., the trios having an offspring trait value between a priori defined thresholds are excluded from the analysis. Keeping intact the ideology and construction of these tests, we propose here an extreme-offspring design for the trios: for each parent pair of which at least one is heterozygous at a marker locus, the offspring having the most extreme trait value is selected for the trio. Our simulation studies show that the effect of the extreme-offspring design can be quite substantial (up to 30% increase in test power), and that the increase is greater for smaller values of the association parameter and for traits with smaller heritability: just those cases where the increase in power is especially desirable.
authors.affiliation: Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. idak@post.tau.ac.il
authors.forename: Ida
authors.initials: I
authors.lastname: Malkin
authors.forename: Emil
authors.initials: E
authors.lastname: Ginsburg
authors.forename: Robert C
authors.initials: RC
authors.lastname: Elston
mesh_terms: D003627:Data Interpretation, Statistical; D030342:Genetic Diseases, Inborn / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics*; D008957:Models, Genetic; D015233:Models, Statistical; D019655:Quantitative Trait, Heritable; D015203:Reproducibility of Results