Knockout mice for a P450 gene cluster

The invention relates to the generation of mouse models of drug metabolism in which clusters of genes that are involved in drug metabolism have been knocked out. The development of new drugs and chemicals for therapeutic use or for other purposes is extremely complex. Of particular importance is the understanding of how these chemical agents are handled in the body, whether they have appropriate pharmacokinetics and whether, as a consequence of metabolism, any safety issues arise. Many of the proteins that are involved in the metabolism, disposition and elimination of drugs are members of multigene families that exhibit very marked species differences in gene number, function and regulation. For these reasons, experiments carried out in laboratory animals to establish routes of metabolism or toxicity can be severely compromised and, as a consequence, do not faithfully represent the human situation. One example of this complexity is reflected in the mammalian cytochrome P450 system, where the sizes of multigene families of proteins which carry out particular metabolic functions vary enormously between species.