GENETICS 101: COMMON INHERITED CLOTTING DISORDERS

Inherited thrombophilia occurs whenan inherited DNA mutation results in thebody producing too much or too little ofa clotting protein or if the clotting proteindoes not function correctly. There are anumber of hereditary clotting disorders,but the 2 most common are factor VLeiden and prothrombin G20210A mutations.

Factor V Leiden causes factor V proteinto be abnormally shaped and prevents itfrom being broken down by proteins Cand S. About 5% of Caucasians carry thismutation, while only 1% to 2% of AfricanAmericans, Hispanic Americans, andNative Americans are affected. A prothrombingene mutation causes theaffected individual to produce too muchof the prothrombin protein, which increasesthe tendency to clot. Prothrombingene mutations occur in 2% to 4% ofCaucasians and about 0.4% of AfricanAmericans. It is rarer in other groups.

A genetic predisposition to clottingdoes not mean that the patient will definitelyhave a blood clot, but knowledgeof the problem may be useful for a numberof reasons. For example, women whoare affected may need to avoid estrogencontainingoral contraceptives and mayrequire use of anticoagulants duringpregnancy, since clotting risk increasesin pregnancy. Patients who have knownthrombophilia should be counseledregarding the signs and symptoms ofthromboembolism and be advised totake these symptoms seriously.

Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Carein High Point, NC.