Nakatani Takuya, Imamura Toshihiko, Ishida Hiroyuki, Wakaizumi Katsuji, Yamamoto Tohru, Otabe Osamu, Ishigami Tsuyoshi, Adachi Souichi, Morimoto Akira
Department of Pediatrics, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan.
Pediatr Blood Cancer. 2008 Dec;51(6):802-5. doi: 10.1002/pbc.21730.
Pediatric essential thrombocythemia (ET) is a rare and heterogenous disease entity. While several recent studies have focused on the role of the JAK2 V617F mutation in pediatric ET, the frequency of pediatric ET cases with this mutation and the associated clinical features remain unclear.
We examined six childhood cases who had been diagnosed with ET according to WHO criteria (onset age: 0.2-14 years) for the presence of the JAK2 V617F mutation, MPLW515L mutation and JAK2 exon 12 mutations. Two sensitive PCR-based methods were used for the JAK2 V617F genotyping. We also examined the expression of polycythemia rubra vera-1 (PRV-1), which is a diagnostic marker for clonal ET.
We found that three of the six cases had the JAK2 V617F mutation and that all six cases expressed PRV-1 in their peripheral granulocytes. Neither MPL W515L mutation nor JAK2 exon 12 mutations was detected in the patients without JAK2 V617F mutation. The two patients who developed thrombocythemia during infancy were JAK2 V617F-negative.
These findings suggest that the JAK2 V617F mutation is not rare in childhood sporadic ET cases, and that these cases might be older and myeloproliferative features.
儿童原发性血小板增多症（ET）是一种罕见的异质性疾病实体。虽然最近有几项研究关注JAK2 V617F突变在儿童ET中的作用，但具有该突变的儿童ET病例的频率以及相关临床特征仍不清楚。
我们检查了6例根据世界卫生组织标准诊断为ET的儿童病例（发病年龄：0.2 - 14岁），以检测JAK2 V617F突变、MPLW515L突变和JAK2外显子12突变的存在情况。使用两种基于聚合酶链反应的敏感方法进行JAK2 V617F基因分型。我们还检测了真性红细胞增多症-1（PRV-1）的表达，PRV-1是克隆性ET的诊断标志物。
我们发现6例病例中有3例存在JAK2 V617F突变，并且所有6例病例的外周粒细胞均表达PRV-1。在没有JAK2 V617F突变的患者中未检测到MPL W515L突变和JAK2外显子12突变。在婴儿期发生血小板增多症的2例患者为JAK2 V617F阴性。
这些发现表明，JAK2 V617F突变在儿童散发性ET病例中并不罕见，并且这些病例可能年龄较大且具有骨髓增殖特征。
