Deep venous thrombosis is the presence of blood clots, usually in the legs that lead to either local problems or breathing problems if the clot moves to the lungs. This study is designed to assess both clinical conditions as well as common genetic factors that lead to more risk of deep venous thrombosis. Clinical conditions of venous thrombosis include: stroke, malignancy, and situations such as surgery, pregnancy, trauma, or travel.

Patients must be 18 years with the ability to understand and consent to questionnaire and blood draw, including understanding of genetic testing..