Gene-targeting studies in mice have made significant contributions to the understanding of molecular genetics. The 2007 Nobel Prize for Medicine was awarded to Mario R. Capecchi, Oliver Smithies and Sir Martin J. Evans for their work on breakthrough discoveries leading to the development of a system for in vivo manipulation of mouse gene expression.

The technique devised by the trio involves the introduction of a genetic change into mouse embryonic stem cells. These embryonic stem cells are subsequently injected into mouse embryos. The mice born from these modified embryos are reared and bred with other mice to produce offspring with the altered genes.

The development of this mouse gene-targeting protocol has uncovered the roles of genes in mammalian organ development as well the cultivation of allele-specific mouse strains. These strains have been used to study parallel human afflictions in mice such as cystic fibrosis, high blood pressure and heart disease.