Briton wins Nobel Prize in medicine

Sir Martin Evans, professor of mammalian genetics at Cardiff University, played a key role in the creation of genetically engineered mice that replicate human diseases.

Commonly known as "knockout mice", they have targeted genes which are inactivated, or silenced.

The rodents are now the universal test-bed for all areas of biomedicine, from basic research into human diseases to the development of new treatments.

Using the technique, mice have been bred with medical conditions ranging from cancer to heart disease and cystic fibrosis. To date, scientists have "knocked out" more than 10,000 mouse genes.

Sir Martin, 66, shares the £755,000 Nobel prize in physiology or medicine with two naturalised Americans, British-born Professor Oliver Smithies, from the University of North Carolina, and Italian-born Professor Mario Capecchi, from the University of Utah.

Together they made a series of ground breaking discoveries involving the manipulation and disabling of mouse genes.

Sir Martin's chief contribution was to use special cells extracted from early-stage mouse embryos to deliver inherited genetic modifications. These cells later became known as embryonic stem cells, now being investigated as potential treatments for disease thanks to their ability to develop into different kinds of tissue. Today, Sir Martin is widely credited with their discovery.

The experiments showed that stem cells could be genetically altered in the laboratory, then injected into mouse embryos to create offspring with changes to their DNA that would be passed on to future generations.

Meanwhile, Capecchi and Smithies had shown how particular genes in mammalian cells could be modified through a process called homologous recombination.