High risk patients include older patients (>60 years), history of thrombosis, platelet count >1500 m/ml, which is paradoxically associated with an increased risk of GI tract bleeding in young women, obesity, cardiovascular risk factors and markers of hypercoagulability such as factor V Leiden and antiphospholipid antibodies [12]. The gene discussed is F5; the disease is obesity due to melanocortin 4 receptor deficiency.