If I have a family member who has had a blood clot or thrombophilia, but I have never had a blood clot, what are my risks?

Your risk may depend on whether you have inherited a tendency to form blood clots. As discussed earlier, clots can occur either sporadically or in response to certain risk factors (for example, trauma, pregnancy, and immobility). Another risk factor is related to your genes, including whether these genes, if inherited, might increase your susceptibility to developing a blood clot. Mutations within genes can be transmitted from generation to generation.

Thrombophilia is a predisposition to the development of blood clots that can result from mutations within genes. It can be either inherited or acquired during a person’s lifetime.

Inherited forms of thrombophilia are transmitted through genes and include factor V Leiden, prothrombin gene mutation, protein S deficiency, protein C deficiency, antithrombin deficiency, and some cases of elevated levels of homocysteine or factor VIII. There may be other inherited forms of thrombophilia that have not yet been discovered.

Inherited thrombophilia can increase a person’s lifetime risk of a DVT or PE from 2 to 100 times. If an individual inherits one copy of a gene mutation, his or her risk of developing a blood clot is higher than normal. If an individual inherits two copies of a gene mutation (either the same mutation for an inherited thrombophilia or two different thrombophilias), his or her risk is much higher than normal.