The nature and identification of quantitative trait loci: A community's view

Abstract

This white paper by eighty members of the Complex Trait Consortium presents a community’s view on the approaches and statistical analyses that are needed for the identification of genetic loci that determine quantitative traits. Quantitative trait loci (QTLs) can be identified in several ways, but is there a definitive test of whether a candidate locus actually corresponds to a specific QTL? Much of the genetic variation that underlies disease susceptibility and morphology is complex and is governed by loci that have quantitative effects on the phenotype. Gene–gene and gene–environment interactions are common and make these loci difficult to analyse. Here, we present a community’s view on the steps that are necessary to identify genetic loci that govern quantitative traits, along with a set of interpretive guidelines. This community mostly represents interests in the analyses of rodent quantitative trait loci (QTLs), although many of the same principles apply to other species. With the development of new genetic techniques and with more information about the mammalian genome, we are confident that QTLs will become easier to identify and will provide valuable information about normal development and disease processes.