Statistical Methods for QTL Mapping

Abstract

Many biologically and economically important traits in higher organisms are quantitative, not qualitative. Traits such as hypertension, diabetes and some genetic diseases in human; height, maturity, stress tolerance and yield of grain in crops; body fat percentage and weight gain in mice; egg and milk production in animals, are all examples of quantitative traits. Genes controlling quantitative traits are called quantitative trait loci (QTL). With the understanding of QTL, it is possible to diagnose human diseases in early stage, breed or genetically engineer superior organisms to obtain desired characteristics such as increased yield and improved quality. In recent years, the advent of fine-scale genetic marker maps for various organism by molecular biology techniques has greatly facilitated the study of QTL systematically. Introduction of QTL mapping and statistical methods for locating the positions and estimating the effects of QTL using genetic marker data as well as the related statistical issues are presented and discussed. Simulated and real examples are used for illustration.