WHO: World Health Organization; PB: peripheral blood; PV: polycythemia vera; ET: essential thrombocythemia; BCR-ABL1: Philadelphia chromosome; CML: chronic myeloid leukemia; PMF: primary myelofibrosis; PDGFRA/B: platelet-derived growth factor receptor A/B; PCM1: pericentriolar material 1; JAK2: Janus kinase 2; FGFR1: fibroblast growth factor receptor 1; CSF3R: colony-stimulating factor 3 receptor. The gene discussed is FGFR1; the disease is primary myelofibrosis.