Mutations of JAK2 and TET2, but not CBL are detectable in a high portion of patients with refractory anemia with ring sideroblasts and thrombocytosis

The WHO classification of 2008 characterized refractory anemia with ring sideroblasts associated with marked thrombocytosis (RARS-T) by the presence of less than 5% marrow blasts, 15% or more ring sideroblasts and a persistent platelet count over 45010 9 /L to be in line with the revised classification of essential thrombocytosis (ET). RARS-T forms a provisional entity with clinical and morphological features of both MDS and BCR-ABL negative myeloproliferative neoplasias (MPN). 1 Although the identification of the JAK2 V617F mutation was an important first step in distinguishing this entity from other hematologic diseases, 2 further genetic characterization is needed.