Quantitative trait loci (QTLs) mapping for growth traits in the mouse: A review

The attainment of a specific mature body size is one of the most fundamenta l differences among species of mammals. Moreover, body size seems to be the central factor underlying differences in traits such as growth rate, energ y metabolism and body composition. An important proportion of this variabil ity is of genetic origin. The goal of the genetic analysis of animal growth is to understand its "genetic architecture", that is the number and positi on of loci affecting the trait, the magnitude of their effects, allele freq uencies and types of gene action. In this review, the different strategies developed to identify and characterize genes involved in the regulation of growth in the mouse are described, with emphasis on the methods developed t o map loci contributing to the regulation of quantitative traits (QTLs).