In this issue of Blood, Tefferi et al make the important observations that polycythemia vera (PV) is not a continuum from essential thrombocythemia (ET), that survival in ET is less than matched controls but of longer duration than in patients with PV and primary myelofibrosis (PMF), and that “triple negative” mutational status in PMF is an important adverse risk factor for blast transformation. Genetic profiling should be integrated into classical methods for profiling these diseases
