Myelodysplastic syndrome and myeloproliferative neoplasm with ring sideroblasts (RS) and thrombocytosis are renamed MDS/MPN with SF3B1 mutation and thrombocytosis, in the presence of an SF3B1 mutation of any VAF (WHO-HAEM5) or VAF ≥ 10% (ICC). The gene discussed is SF3B1; the disease is myeloproliferative disorder.