The V617F JAK2 mutation and the myeloproliferative disorders

The discovery this year of a single mutation in the Janus Kinase (JAK)-2 gene in a high percentage of cases of polycythaemia vera (PV), essential thrombocythaemia (ET) and myelofibrosis suggests that it maybe the underlying molecular mechanism for these disorders. Different approaches from the inhibition of the tyrosine kinase JAK2, widespread search for mutations in tyrosine kinases, and investigation of the short arm of chromosome 9 where JAK2 is located all led to the discovery of the V617F JAK2 mutation. Substitution of a valine for a phenylalanine destabilizes the JH2 domain of JAK2 causes loss of the auto-inhibitory activity of this domain and explains some of the biological phenomena observed in patients with myeloproliferative disorders (MPD). The V617F JAK2 mutation can be detected by PCR-direct sequencing using DNA from the granulocyte lineage or with increased sensitivity by the amplification refractory mutation system using DNA from unfractionated blood. Pyrosequencing assays can be used to quantitate allele ratios to accurately define homozygote and heterozygote status. This single mutation is widespread having been detected in related MPD and other haematological malignancies. This leads to a number of further questions about the role of this single mutation in the clinical pattern of disease.     

The JAK2V617F tyrosine kinase mutation in myeloproliferative disorders: Summary of published literature and a perspective

A common somatic point mutation has recently been identified in the Janus kinase 2 (JAK2) gene in virtually all cases of polycythemia vera and in a majority of patients with essential thrombocythemia and idiopathic myelofibrosis. This common mutation in the pseudokinase autoinhibitory domain of the enzyme results in constitutive tyrosine kinase activation, which in turn leads to cytokine hypersensitivity and factor independence in factor-dependent cell lines, and causes polycythemia in mice. This discovery has led to greater understanding of the molecular pathogenesis of the chronic myeloproliferative disorders, which may translate into targeted therapy.     

JAK2基因突变与骨髓增生性疾病的关系

 骨髓增生性疾病（MPD）中真性红细胞增多症（PV）、特发性血小板增多症（ET）、特发性骨髓纤维化（IMF）发现蛋白酪氨酸激酶（JAK2）基因上有一个碱基突变JAK2 V617F,突变明显与PV、ET和IMF的发生有关,这一发现可能成为诊断这类综合征的一种方式,也为寻找新的药物治疗MPD提供了明确的作用目标,同时还为研究细胞生长紊乱和细胞功能紊乱提供新的研究思路。     

bcr-abl阴性骨髓增生性疾病患者JAK2V617F点突变检测的临床意义

目的 探索Janus Kinase 2V617F基因突变(JAK2V617F)在bcr-abl阴性骨髓增生性疾病(MPD)的发生率和临床意义.方法 基因组DNA从患者骨髓或外周血粒细胞中提取.采用等位基因特异性PCR(AS-PCR)、限制性内切酶消化和PCR产物测序的方法检测JAK2V617F突变.共检测患者110例,其中bcr-abl阴性MPD 41例、bcr-abl阳性慢性粒细胞白血病(CML)25例和急性白血病44例.结果 JAK2V617F阳性结果分别为真性红细胞增多症(PV)11例(91.7%)、原发性血小板增多症(ET)8例(53.3%)、特发性骨髓纤维化(IMF)4例(57.1%),而高嗜酸粒细胞增多症(HES)7例、bcr-abl阳性CML 25例和急性白血病44例[包括急性髓细胞白血病(AML)24例、急性淋巴细胞白血病(ALL)18例、急性混合细胞白血病2例1均未检测到JAK2V617F基因突变.在所有JAK2V617F阳性的标本和10份阴性标本中,AS-PCR和限制性内切酶消化方法的测定结果都可经测序进一步证实.结论 90%以上的PV、50%以上的ET和IMF可检测到JAK2V617F基因突变;JAK2V617F基因突变在PV、ET和IMF的诊断和鉴别诊断中有重要意义,可以作为诊断的分子标志,也可能是治疗的新靶点.     

伴有JAK2 V617F突变的慢性中性粒细胞白血病1例并文献复习

目的：探讨伴有JAK2基因V617F突变的慢性中性粒细胞白血病（CNL）的实验室特征。方法：通过骨髓涂片进行细胞形态学分析诊断;采用实时荧光定量PCR方法检测BCR-ABL融合基因;实时荧光定量PCR方法及DNA测序方法检测JAK2 V617F突变;RHG显带进行常规染色体核型分析。结果：细胞形态学诊断为慢性中性粒细胞白血病;BCR/ABL融合基因为阴性;存在JAK2 V617F杂合突变;染色体分析结果为正常核型。结论：JAK2 V617F突变在慢性中性粒细胞白血病中很少见,具有该突变的CNL患者有较长的生存期,JAK2 V617F突变可能提示预后良好。     

伴有JAK2 V617F突变的慢性中性粒细胞白血病1例并文献复习

目的:探讨伴有JAK2基因V617F突变的慢性中性粒细胞白血病(CNL)的实验室特征。方法:通过骨髓涂片进行细胞形态学分析诊断;采用实时荧光定量PCR方法检测BCR-ABL融合基因;实时荧光定量PCR方法及DNA测序方法检测JAK2 V617F突变;RHG显带进行常规染色体核型分析。结果:细胞形态学诊断为慢性中性粒细胞白血病;BCR/ABL融合基因为阴性;存在JAK2 V617F杂合突变;染色体分析结果为正常核型。结论:JAK2 V617F突变在慢性中性粒细胞白血病中很少见,具有该突变的CNL患者有较长的生存期,JAK2 V617F突变可能提示预后良好。     

JAK2 V617F基因突变阳性骨髓增殖性肿瘤治疗研究进展

JAK2 V617F基因突变阳性骨髓增殖性肿瘤(MPN)由真性红细胞增多症(PV)、原发性血小板增多症(ET)和原发性骨髓纤维化(PMF)组成.文章聚焦于其危险度积分系统和治疗进展,包括一线及二线治疗、JAK2抑制剂、降细胞治疗、抗纤维化和其他单药或联合治疗.     

A quantitative assay for JAK2(V617F) mutation in myeloproliferative disorders by ARMS-PCR and capillary electrophoresis.

A point mutation in the Janus tyrosine kinase 2 (JAK2) gene has been described in patients with chronic myeloproliferative disorders (MPD), but the clinical significance of JAK2(V617F), which may be harbored in either the heterozygote or homozyote status, is still largely undefined. There are indirect suggestions that clinical phenotype and also some biological characteristics are dependent on the mutated allele levels. We have designed and validated in 179 MPD patients an amplification-refractory mutation sequencing PCR assay that allows the relative quantitation of mutated and normal JAK2 mRNAs using dye-labelled mutation-specific primers and capillary electrophoresis. Direct sequencing confirmed the specificity of the assay, which has a detection limit congruent with1% and allowed to identify 9% more JAK2-mutated patients as compared to conventional allele-specific PCR. The mutated mRNA ratio ranged from 5 to 51% in the JAK2(V617F) heterozygote and from 45 to 100% in the homozygote patients. Expression levels of both PRV-1 and NF-E2 gene, previously found to be overexpressed in MPD patients, were significantly correlated to the amount of mutated JAK2 mRNA. We propose that this method might complement current technologies based on genomic DNA analysis, and lead prospectively to a better clinically oriented assessment of the impact of JAK2(V617F) mutation in MPD.     

骨髓增殖性肿瘤120例JAK2 V617F基因突变的临床分析

目的 探讨JAK2 V617F基因突变在骨髓增殖性肿瘤(MPN)患者中的发生率及临床意义.方法 采用骨髓细胞学和活组织检查方法分析120例患者的骨髓病理状况,监测费城染色体(Ph染色体)和bcr-abl融合基因.从患者骨髓抽提DNA,采用荧光定量PCR技术检测JAK2 V617F基因突变.结果 所有患者均呈现出MPN各自类型的典型特征.Ph染色体和bcr-abl融合基因检测均为阴性.120例MPN患者中JAK2 V617F基因突变的阳性率为66.7％(80/120),其中真性红细胞增多症(PV)为72.7％(16/22),原发性血小板增多症(ET)为66.0％(62/94),4例原发性骨髓纤维化(PMF)患者中2例阳性.JAK2 V617F突变阳性PV患者的外周血白细胞计数(P=0.001)和血小板计数(P=0.010)均高于阴性患者;JAK2 V617F突变阳性ET患者的白细胞计数高于阴性患者(P=0.006);PMF中JAK2V617F突变阳性和阴性患者间各项指标差异均无统计学意义(均P＞0.05).结论 JAK2 V617F基因突变检测有助于bcr-abl阴性MPN的诊断和鉴别诊断,使患者能够在早期被发现和治疗.     

BCR-ABL阴性骨髓增殖性疾病患者

目的：检测BCRABL融合基因阴性的骨髓增殖性疾病（myeloproliferative disorders,MPD）患者的JAK2 V617F突变率,探讨其与MPD患者临床特征间的关系。方法：选择山东大学附属省立医院确诊的56例BCRABL阴性的MPD患者为研究对象,其中真性红细胞增多症（polycythaemia vera,PV）20例、原发性血小板增多症（essential thrombocythaemia,ET）26例,特发性骨髓纤维化（idiopathic myelofibrosis,IMF）10例。应用等位基因特异性PCR（allelespecific polymerase chain reaction,ASPCR）和基因测序检测MPD患者JAK2 V617F突变情况,分析各组MPD患者JAK2 V617F突变与MPD临床特征间的关系。结果：56例MPD患者中36例检出JAK2 V617F突变,突变率分别为ET患者53.8%（14/26）,PV患者85%（17/20）,IMF患者50%（5/10）。JAK2 V617F突变阳性的MPD患者与突变阴性者相比,在血象方面：PV患者的白细胞（P= 0.018）、血小板计数（P= 0.021）;ET患者的白细胞计数（P= 0.001）、血红蛋白（P= 0.007）;IMF患者的白细胞计数（P= 0.026）差异均有统计学意义。在并发症方面：ET组中JAK2 V617F突变阳性的患者出血、血栓并发症的发生率更高（P= 0.016）,PV及IMF组中差异无统计学意义。结论：ASPCR可有效检测JAK2 V617F突变的发生,JAK2 V617F突变阳性的MPD患者与突变阴性者在临床特征上有较明显的差异。     

BCR-ABL阴性骨髓增殖性肿瘤JAK2 V617F基因突变状态及负荷的临床意义

目的探讨JAK2 V617F基因突变状态及负荷对BCR-ABL阴性骨髓增殖性肿瘤(MPN)的影响。方法回顾性分析2015年9月至2020年1月河北省沧州市中心医院199例MPN患者的临床资料。分析JAK2 V617F突变负荷与MPN患者临床病理特征及预后评分的关系。结果199例BCR-ABL阴性MPN患者中JAK2 V617F突变阳性138例(69.4%);其中,72例真性红细胞增多症(PV)患者中突变阳性64例(88.9%),101例原发性血小板增多症(ET)患者中突变阳性54例(53.5%),25例骨髓纤维化(MF)患者中突变阳性20例(80.0%),1例嗜酸粒细胞增多症(HES)患者突变阳性。JAK2 V617F突变高负荷者占55.1%(76/138)。突变负荷最高的类型为PV,MF次之,ET最低,3组突变负荷分别为(73.9±18.3)%、(59.9±25.2)%、(25.0±16.5)%。JAK2 V617F突变负荷与PV、ET、MF患者的白细胞计数均呈正相关(r值分别为0.626、0.675、0.796,均P<0.01)。JAK2 V617F突变负荷与PV、ET患者的预后评分均呈正相关(r值分别为0.296、0.404,均P<0.05)。结论BCR-ABL阴性MPN患者JAK2 V617F突变负荷与临床病理因素相关,JAK2 V617F突变高负荷患者预后不良。     

骨髓增殖性肿瘤JAK2V617F基因突变与疾病临床特征相关性的分析※

 摘要：目的：研究我区骨髓增殖性肿瘤（MPN）中JAK2V617F基因突变与疾病临床特征的相关性。方法：回顾性分析我区134例MPN患者JAK2V617F基因突变与患者性别、年龄、民族、外周血白细胞、血小板计数、血红蛋白、血清乳酸脱氢酶（LDH）水平及是否合并血栓、出血及心血管疾病并发症等临床特征的相关性进行统计分析。结果：134例MPN患者中PV 51例,ET 66例,IMF17例,存在JAK2V617F突变98例（73.1%）。年龄60岁以上者发生突变率较60岁以下者明显增高（p＜0.05）,MPD患者中JAK2V617F突变阳性者外周血白细胞计数、血红蛋白水平与血栓、心血管疾病的发生率均高于突变阴性者（p＜0.05）,而性别、民族、血小板计数及LDH水平在JAK2V617F基因突变阳性与阴性患者间无显著性差异（p＞0.05）。结论：MPN患者JAK2V617F基因突变与MPN患者年龄、外周血白细胞计数、血红蛋白水平、血栓及心血管疾病并发症相关。