Genetic variation involved in response to anti-clotting drug

Reported by Susan Aldridge, PhD, medical journalist

Scientists have discovered a gene that is involved in individual responses to the anti-clotting drug warfarin.
People are often prescribed warfarin, which reduces the risk of blood clotting, after a stroke or a heart attack. But it can be hard to determine the correct dose for an individual patient - too little and it will not be effective, too much and there is a risk of bleeding. A team at the University of Washington, Seattle, and at Washington University, St Louis, now reveal that a genetic variant may explain why people differ so in the dose of warfarin they require.

The gene, called VKORC1, is involved in the clotting process. The researchers looked at the variants of the gene present in a group of 186 patients on warfarin. Those with a specific variant seemed to do well on similar doses of warfarin. It may be that genetic screening could help determine the exact dose of warfarin a person should take - low, intermediate or high - to be effective without putting them at risk of side effects.

Source
New England Journal of Medicine 2nd June 2005