In this paper we present a novel method for selecting optimally informative
sibships of any size for quantitative trait locus (QTL) linkage analysis.
The method allocates a quantitative index of potential informativeness to e
ach sibship on the basis of observed trait scores and an assumed true QTL m
odel. Any sample of phenotypically screened sibships can therefore be easil
y rank-ordered for selective genotyping. The quantitative index is the sibs
hip's expected contribution to the non-centrality parameter. This expectati
on represents the weighted sum of X-2 test statistics that would be obtaine
d given the observed trait values over all possible sibship genotypic confi
gurations; each configuration is weighted by the likelihood of it occurring
given the assumed true genetic model. The properties of this procedure are
explored in relation to the accuracy of the assumed true genetic model and
sibship size. In comparison to previous methods of selecting phenotypicall
y extreme sibships for genotyping, the proposed method is considerably more
efficient and is robust with regard to the specification of the genetic mo
del. Copyright (C) 2001 S. Karger AG, Basel.