We can find JAK2 V617F and TET2 mutations in some patients of myeloproliferative neoplasm. JAK2 V617F mutation has different effects on regulating gene expressions, depending on whether TET2 mutation is present or not. In addition, when JAK2 V617F and TET2 mutations are both present, which mutation appears first also affects certain properties of patients. We use nonlinear ordinary differential equation models and Markov chain models to explain such phenomena.