Moreover, disease related factors, such as increased blood cell counts, and mostly the presence of the JAK2 mutation, can interact with patient related factors, such as age, history of previous thrombotic events, obesity, hypertension, hyperlipidemia, thrombophilia and other known risk factors for thromboembolism increasing the risk of thrombosis. Here, JAK2 is linked to obesity due to melanocortin 4 receptor deficiency.