Mouse and other mammalian genes with interesting phenotypic variation are determined mainly by quantitative trait loci (QTL). Identifying these complex and quantitative traits remains extremely difficult, although methods and resources are rapidly improving. In his paper Shalkwyk discusses many approaches to identify the genes for traits including using QTL mapping of inbred strains. However inbreeding increases the amount of recombination in the animals. During inbreeding some become fixed either from homozygous individuals or by genetic drift. To reduce drift, short term selection may be a viable alternative to extended inbreeding programs. A traditional approach to genetic mapping is to cross two inbred strains and backcross one of the F1 with one of the parental strains to produce F2 generation which are then phenotyped. Shalkwyk also discusses the use of Genetic Reference Populations(GRP), which allows data to be aggregated amongst labs through time, and Recombinant Inbred (RI) panels or a combination of both as possibly having huge potentials for locating genes and their potential for causing phenotypic variance. RI panels allows for testing across a range of environments using as many replicates as needed on test-naïve individuals. Recently two large RI panels have become available which improves the ability to detect QLT of small effect.
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Schalkwyk, L.C. 2005. Complex trait approaches to the analysis of behaviour in the mouse. Psychiatry 12: 18-21
