title: Low neutrophil alkaline phosphatase score is a new aspect of calreticulin-mutated myeloproliferative neoplasms.
abstract: Calreticulin (CALR) and JAK2-V617F gene mutations, which are major genetic mutations in patients with primary myelofibrosis (PMF) and essential thrombocythemia (ET), exert different effects on the clinical features and outcomes of these diseases. We analyzed 88 and 9 patients with ET and PMF, respectively, and determined the differences in the clinical characteristics of ET patients with JAK2-V617F compared with CALR mutations. The frequency of the JAK2-V617F and CALR mutations were 64 and 22 %, respectively. Patients with CALR mutations were younger, had a lower white blood cell count, and had a lower rate of thrombotic events than patients with the JAK2 mutation. The neutrophil alkaline phosphatase (NAP) score of 16 patients with CALR mutations was significantly lower than the normal controls, which was mainly due to the high proportion of NAP-negative neutrophils. This is the first report to show an association between CALR mutations in patients with myeloproliferative neoplasms (MPN) and the NAP score. Although the mechanism is unclear, the NAP score could be a useful and reliable biochemical marker to discriminate the mutational status of MPN patients. Further investigation is warranted to determine whether these characteristics contribute to the pathogenesis of MPN and the NAP score.
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Toshinori
authors: T
authors: Kondo
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan ; Department of Transfusion Medicine and Cell Therapy, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe City, Saitama Prefecture 350-8550 Japan.
authors: Taizo
authors: T
authors: Tasaka
authors: Department of Laboratory Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Nanako
authors: N
authors: Tomioka
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Fuminori
authors: F
authors: Sano
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Hirotoshi
authors: H
authors: Tokunaga
authors: Department of Laboratory Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Shin-Ichiro
authors: S
authors: Suemori
authors: Department of Laboratory Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Takayuki
authors: T
authors: Tsujioka
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Yoshiko
authors: Y
authors: Matsuhashi
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Hidekazu
authors: H
authors: Nakanishi
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Hideho
authors: H
authors: Wada
authors: Department of Laboratory Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Kaoru
authors: K
authors: Tohyama
authors: Department of Hematology, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama Prefecture 701-0192 Japan.
authors: Takashi
authors: T
authors: Sugihara
keywords: Alkaline phosphatase score; Calreticulin; Essential thrombocythemia; Janus kinase 2; Myeloproliferative neoplasms