Comprehensive mammalian genetics: history and future prospects of gene trapping in the mouse.

Gene trapping has matured into a tool with tremendous potential for mammalian biology. It both mutates and helps identify genes and can be streamlined so that many thousands of insertions can be characterized. In only a few years most of the genome of the mouse will be tagged and mutated using the latest gene trap designs. By creating such a resource, costly and time consuming alternative methods of mutagenesis and gene identification can be avoided allowing biologists to concentrate on determining gene function in vivo. This will mean a major shift in how the genome will be mined for new drug targets. Notably, gene discovery via gene traps does not suffer from the limitations of other methods as it is not biased by expression level. Mouse strains with specific gene mutations can be easily derived from a gene trap library constructed using embryonic stem cells. These strains will help determine the role of the gene product in mammalian physiology and hence the relevance of the gene product to human disease.