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Gene Targeting

The genetic techniques developed by Professor Sir Martin Evans and his two fellow Nobel Laureates are already bringing huge benefits, having been adopted in laboratories the world over for vital research into hundreds of diseases and disorders.

Yet, just 20 years before their breakthroughs, mainstream scientific opinion regarded such techniques as “impossible.”

Sir Martin shares his Nobel Prize with Professor Mario Capecchi of the University of Utah and UK-born Professor Oliver Smithies of the University of North Carolina.

Professors Capecchi and Smithies had the vision to see that mammalian cells could be genetically modified by a process called homologous recombination. Their experiments suggested that all genes could be modified in this way.

However, the cells they studied could not be used to create lines of animals in which a specific gene had been modified. A new kind of cell was needed, which could give rise to germ cells and allow DNA modifications to be inherited.

Professor Sir Martin Evans in his laboratory

Sir Martin’s contribution was to discover these cells. Initial attempts with carcinoma cells from mice were unsuccessful. However, he then turned his attention to embryonic stem cells. He modified these cells genetically and showed they would create mice which could pass on the new genes to the next generation.

The marriage of Professors Capecchi and Smithies’ homologous recombination technique with Sir Martin’s stem cell discoveries has created the highly versatile new technology of gene targeting.

It is now possible to introduce mice strains (known as “knockout mice”) in which specific genetic modifications can be activitated at specific times, or in specific cells or organs. It is possible to study almost every aspect of mammalian physiology in this way. The technique has been used for research in fields as diverse as cancer, immunology, neurobiology, human genetic disorders and endocrinology.

Sir Martin himself has used the technique in studying cystic fibrosis and breast cancer. Professor Capechi has shed light on the causes of several human birth abnormalities, while Professor Smithies has worked on the blood disease thalassemia and hypertension.

However, scientists are still barely scratching the surface of the full capabilities of gene targeting technology. As the Nobel Assembly said in awarding the prize to the three professors: “Its benefits to mankind will continue to increase over many years to come.”