Exotic mice as models for aging research: polemic and prospectus by R. Miller et al.

Miller and colleagues present a polemic against uniform genotypes in gerontological research and a paean for genetically heterogeneous populations. Both on simple sampling considerations, and because of selective loss of alleles through inbreeding depression, inbred strains are idiosyncratic, and the lack of genetic variance within strains limits their utility in examining relationships among phenotypes. Heterogeneous stocks, by contrast, are not impaired by inbreeding depression, and the presence of genetic and environmental variance provides for effective assessment of correlations among variables. Those assembled by intermating of inbred strains are replicable in terms of gene pool parameters, even if no individual can ever be replicated, and those derived from wild-trapping may include alleles absent for whatever reason from current laboratory strains. This author concurs that there are limitations on research with uniform genotypes and advantages of heterogeneous populations. However, for specific purposes, the uniformity and stability of inbred strains are extremely valuable attributes, and heterogeneous stocks have their own limitations. Researchers should select the animal model most appropriate for their specific purpose.