Power of a score test for quantitative trait linkage analysis of relative pairs

The score test of Dudoit and Speed [(2000) Biostatistics 1:1-26] to detect linkage between a trait locus and a marker locus, using identity by descent data on sib pairs, is extended to other types of relative pairs (grandpare nt/grandchild, avuncular, and half-sib relationships). The test is based on the likelihood of the recombination fraction theta between trait and marke r loci, conditional on phenotypes of the relatives. We present results of s imulation studies characterizing power and robustness properties of this li nkage score test, and compare the power of the score test to that of the cl assical and modified Haseman-Elston tests. The score test has considerable power, particularly under sampling schemes where selection is on double pro bands. Use of a generic additive model [Goldstein et at., submitted] with a llele frequency p = 0.2, heritability H = 0.3, and a moderate residual corr elation of rho = 0.2 resulted in a very good overall performance across a w ide range of trait-generating models. Genet. Epidemiol. 19(Suppl 1):S85-S91 , 2000. (C) 2000 Wiley-Liss, Inc.