title: Methods for multiple-marker mapping of quantitative trait loci in half-sib populations.
abstract: In this paper we consider the detection of individual loci controlling quantitative traits of interest (quantitative trait loci or QTLs) in the large half-sib family structure found in some species. Two simple approaches using multiple markers are proposed, one using least squares and the other maximum likelihood. These methods are intended to provide a relatively fast screening of the entire genome to pinpoint regions of interest for further investigation. They are compared with a more traditional single-marker least-squares approach. The use of multiple markers is shown to increase power and has the advantage of providing an estimate for the location of the QTL. The maximum-likelihood and the least-squares approaches using multiple markers give similar power and estimates for the QTL location, although the likelihood approach also provides estimates of the QTL effect and sire heterozygote frequency. A number of assumptions have been made in order to make the likelihood calculations feasible, however, and computationally it is still more demanding than the least-squares approach. The least-squares approach using multiple markers provides a fast method that can easily be extended to include additional effects.
authors.affiliation: INRA Station de Génétique Quantitative et Appliquée, Jouy-en-Josas, France.
authors.forename: S A
authors.initials: SA
authors.lastname: Knott
authors.forename: J M
authors.initials: JM
authors.lastname: Elsen
authors.forename: C S
authors.initials: CS
authors.lastname: Haley