Background: Beta-thalassemia (β-thalassemia) is characterized by abnormalities in the synthesis of the hemoglobin subunit beta(hemoglobin beta chain), resulting in anemia of different degrees of severity1.ET is a chronic MPN, characterized by the clonalproliferation of megakaryocytes in the bone marrow and a high platelet count in the peripheral blood2. JAK2/V617F mutationscreening is part of the diagnostic workup for ET, according to the World Health Organization. The combination ofmyeloproliferative neoplasias (MPN) and β-thalassemia is extremely unusual. Only several cases of concurrent β-thalassemia andpolycythemia vera (PV) have been reported thus far in the literature3 Aims: ET in β-thalassaemic patients has not been previously described. To our knowledge, this is the first report on coexistence of β-thalassemia and ET. Methods: A 24-year-old female, diagnosed with β-thalassemia and underwent splenectomy in childhood, was evaluated for alifelong history of anemia and thrombocytosis. The outcome of her genetic test was shown in figure 1the mutant site of beta-globingene is in IVS-2-654which was reported as a common type of beta-thalassemia in Chinese Results: A research group investigated the status of thalassemia in Guangxi, China. The study shows that IVS-2-654 mutationsaccount for 5.8% of β-thalassemia 7whereas another study found Cd 41/42 (-TTCT) and IVS 2-654 (C-T) mutations were mostcommon among the Chinese (79.1%)8. Her blood routine monitoring results in moderate anemia and high platelet count. Hercomplete blood count showed white blood cells, 9.6 × 10 12/L; red blood cells, 3.61 × 1012/L; hemoglobin, 85 g/L; mean corpuscularvolume, 78.6fL; and platelets, 393 × 109/L. During the follow-up, her platelet counts had risen to as high as 650 × 109/L. Measures ofinflammation including erythrocyte sedimentation rate and C-reactive protein were normal and no clinical signs of infection weredetectable to explain marked thrombocytosis. A myeloproliferative disorder was considered. To confirm the disease, a bone marrowbiopsy were performed, showing prominent conspicuous megakaryocyte proliferation in clusters and mild bone marrow reticulinfibrosisFig. 2. Conventional cytogenetics revealed a normal karyogram, and molecular study showed the absence of BCR-ABLtranscript and presence of JAK2/V617F mutation. The diagnosis was established by the presence of the JAK2/V617F mutation, afinding present in approximately 57% of essential thrombocythemia (ET) cases9. In addition, Next-generation sequencing showed atotal of 114 variants with 47.0% of pathological mutations in EP300c.1519AG;p.S507G51.1% in CUX1(c.328GA;p.D110N), and 47.0% in FGFR3 c.1738GA;p.D580N Summary/Conclusion: In summary, this is the first report of Coexistence of β-thalassemia and Essential Thrombocythaemia. Theacquired mutation of CUX1EP300 and FGFR3 plays a potential role in disease progression and transformation. ∗∗Correspondence to: Dr Jian Huang, E-mail: [email protected] AcknowledgmentThe research was supportedby funding of the Science and Technology Department of Zhejiang Province, China(2016C33160), and Yiwu public technologyresearch projects, Zhejiang Province, China (2016-S-05)., the key medical discipline of YiwuChinaHematology2018-2020.