Capitalizing on large-scale mouse mutagenesis screens

Variation is the crux of genetics. Mutagenesis screens in organisms from ba cteria to fish have provided a battery of mutants that define protein funct ions within complex pathways. Large-scale mutation isolation has been carri ed out in Caenorhabditis elegans, Drosophila melanogaster and zebrafish, an d has been recently reported in the mouse in two screens that have generate d many new, clinically relevant mutations to reveal the power of phenotype- driven screens in a mammal.