Clinical Features and Treatment of Patients With Essential Thrombocythemia / 日本農村医学会雑誌

ABSTRACT

We summarized recent findings regarding the clinical features and treatment of patients with essential thrombocythemia (ET), in particular, those with calreticulin (CALR ) mutations. CALR mutations are frameshift mutations of exon 9, which are mainly composed of a 52-bp deletion (Type 1) or 5-bp insertion (Type 2). ET with CALR mutations is associated with younger age, male sex, higher platelet count, lower hemoglobin level, lower leukocyte count, and lower incidence of thrombosis compared with ET with Janus kinase 2 (JAK2 ) mutations. There is no transformation to polycythemia vera in ET patients with CALR mutations. Patients with ET who have CALR type 1 mutations are at higher risk of thrombosis and myelofibrotic transformation compared with ET with CALR type-2 mutations. The standard treatment of CALR-mutated ET patients is currently based on the treatment algorithm of JAK2-unmutated ET patients. Further studies are necessary to clarify whether the appropriate treatment differs between type 1 and 2 mutations of CALR-mutated ET patients.