There are two main types of BCR-ABL-negative myeloproliferative neoplasms: the JAK2V617F myeloproliferative neoplasms (about 70% of cases), which include essential thrombocythemia, polycythemia vera and primary myelofibrosis; and the calreticulin and MPL mutated myeloproliferative neoplasms (20% of cases), which really only include essential thrombocythemia and primary myelofibrosis. Additional somatic mutations are present in these myeloproliferative neoplasms, but they are mainly phenotypic modifiers discriminating between essential thrombocythemia and primary myelofibrosis. This study, together with {1}, showed that these genes, which precede JAK2V617F occurrence, are associated with age-related clonal hematopoiesis, JAK2V617F myeloproliferative neoplasms being secondary to ageing. This Recommendation is of an article referenced in an F1000 Faculty Review also written by William Vainchenker, Stefan N. Constantinescu and Isabelle Plo.