JAK2 and myeloproliferative disorder: Triple-negative are those who are negative for the three mutations (Figure 1).27 Screening for CALR mutation should now be included in the diagnostic work-up of MPN and formally incorporated in future revisions of the WHO classification system.28 Similar to the JAK2V617F mutation, attempts to create a molecular classification of MPN according to JAK2/MPL/CALR mutations are still premature but may be the future of MPN.29