Pill, Gene Defect Tied to Clot Risk

Two gene mutations -- including one found in up to 15% of whites -- and oral contraceptive use are linked to an increased risk of cerebral-vein thrombosis, a potentially fatal disorder caused by clotting in the brain's venous system. Women with one of the gene mutations who also take oral contraceptives have a risk of cerebral-vein thrombosis nearly 150 times that of the general population.

Certain non-genetic factors, including smoking and the use of oral contraceptives, have also been linked to an increased risk for thromboembolism (clotting) in various sites, including the legs, brain, retina, and liver. The Italian researchers found that 20% of the patients with cerebral-vein thrombosis and 3% of the controls carried the prothrombin-gene mutation. Likewise, 15% of cerebral-vein thrombosis patients carried the factor V mutation, compared with just 3% of controls.

The investigators also discovered that the most prevalent non-genetic risk factor for (cerebral-vein thrombosis) was oral contraceptive use,"which raised a woman's risk for the illness to 22 times that of nonusers." The researchers point out that 96% of women suffering from cerebral-vein thrombosis were using the Pill at the time of their illness, compared with just 32% of controls. Finally, they found that in women who were taking oral contraceptives and also had the prothrombin-gene mutation, risk for cerebral vein thrombosis increased to nearly 150 times that of other women.

The New England Journal of Medicine June 18,1998;338:1793-1797, 1840-1841.

COMMENT: It is not very practical to be screened for this genetic mutation at this time. It might be in the future. However, from my perspective, as I mentioned above, it would seem wise for all women to avoid taking oral contraceptives. I can not think of any good reason for someone to take them. As mentioned, above contraceptive options are available. If they are being used for endometriosis or regulation of periods, natural progesterone is much more effective and virtually without side effects.

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