Subsequently, novel insights into Ph-negative MPN development were provided by the identification of the activating mutations in the myeloproliferative leukemia (MPL) gene in 2006 and CALR gene in 2013 (Klampfl et al., 2013; Nangalia et al., 2013; Rumi et al., 2014a). The gene discussed is CALR; the disease is myeloproliferative disorder.