Polycythemia vera: a comprehensive review and clinical recommendations

Prevalence and diagnostic performance of iron deficiency in polycythemia

INTRODUCTION

Several observations have shown that patients with polycythemia have iron deficiency. Our objectives were to report the prevalence of iron deficiency and to evaluate the diagnostic performance of serum ferritin in polycythemia vera.

PATIENTS AND METHOD

This is a retrospective descriptive and analytical study carried out in the internal medicine department of the Henri Mondor Hospital, Aurillac, France. The study involved 114 patients with polycythemia, followed in the department from January 1, 2010 to December 31, 2021. To evaluate the diagnostic performance, the JAK2 mutation was considered as the gold standard of diagnosis.

RESULTS

Thirty-three patients had polycythemia vera and 76 patients had secondary polycythemia. The mean age of the patients was 61.79 years (±15.44) with a sex ratio of 4.43. The overall prevalence of iron deficiency was 21.05%. The prevalence was 53% in polycythemia vera group and 1.32% in secondary polycythemia group. The risk of iron deficiency was high in polycythemia vera (OR = 115; 95% CI [14.4-918.2], p < 0.0001) and the sensitivity and specificity of serum ferritin were 52.63% and 100% respectively.

CONCLUSION

Assessment of iron deficiency should be part of the initial evaluation of polycythemia. Iron deficiency had a high specificity during polycythemia vera.

Bilateral adrenal and pulmonary haemorrhages as an initial presentation of polycythaemia vera

We report a case of a man in his early 60s presenting with bilateral adrenal and pulmonary haemorrhages as an initial presentation of polycythaemia vera (PV). Symptomatology included severe compressive chest pain radiating to epigastrium, with unremarkable physical findings, parameters and ECG. Blood investigations showed an elevated haemoglobin (174 g/L, reference range (RR): 141-172g/L) and haematocrit (55.7%, RR: 40.4%-50.4%) levels.Cross-sectional imaging excluded aortic dissection, but imaging repeated 48 hours after his admission for acute dyspnoea and worsening abdominal pain showed bilateral alveolar and adrenal haemorrhages. Cortisol level was 27 nmol/L (RR: 145-619 nmol/L). Investigations confirming PV included the presence of a Janus kinase 2 (JAK2V617F) gene mutation, hypercellularity with erythroid hyperplasia on bone marrow microscopy and a low serum erythropoietin (2.6 mIU/mL, RR: 4.3-29.0 mIU/mL). Aspirin, hydroxyurea, venesection and cortisol replacement were initiated to get good treatment outcome.

Incidence and risk factors associated with preoperative deep venous thrombosis in the young and middle-aged patients after hip fracture

Objective

This study aims to investigate the incidence, occurrence timing and locations of preoperative DVT and identify the associated factors in this group.

Methods

A retrospective analysis of collected data in young and middle-aged (18–59 years) patients who presented with hip fracture between October 2015 and December 2018 was conducted. Before operation, patients were routinely examined for DVT by Duplex ultrasonography (DUS). Electronic medical records were retrieved to collect the data, involving demographics, comorbidities, injury and laboratory biomarkers after admission. Multivariate logistic regression analysis was performed to identify factors that were independently associated with DVT.

Results

Eight hundred and fifty-seven patients were included, and 51 (6.0%) were diagnosed with preoperative DVT, with 2.5% for proximal DVT. The average age of patients with DVT is 48.7 ± 9.4 year, while that of patients without DVT is 45.0 ± 10.9 year. The mean time from injury to diagnosis of DVT was 6.8 ± 5.5 days, 43.1% cases occurring at day 2–4 after injury. Among 51 patients with DVT, 97 thrombi were found. Most patients had thrombi at injured extremity (72.5%), 19.6% at uninjured and 7.8% at bilateral extremities. There are significantly difference between patients with DVT and patients without DVT in term of prevalence of total protein (41.2% vs 24.4%, P = 0.008), albumin (54.9% vs 25.6%, P = 0.001), low lactate dehydrogenase (51.0% vs 30.3%, P = 0.002), lower serum sodium concentration (60.8% vs 29.9%, P = 0.001), lower RBC count (68.6% vs 37.0%, P = 0.001), lower HGB (51.0% vs 35.1%, P = 0.022), higher HCT (86.3% vs 35.1%, P = 0.022) and higher platelet count (37.3% vs 11.3%, P = 0.001). The multivariate analyses showed increasing age in year (OR 1.04, 95% CI; P = 0.020), delay to DUS (OR, 1.26; P = 0.001), abnormal LDH (OR, 1.45; P = 0.026), lower serum sodium concentration (OR, 2.56; P = 0.007), and higher HCT level (OR, 4.11; P = 0.003) were independently associated with DVT.

Conclusion

These findings could be beneficial in informed preventive of DVT and optimized management of hip fracture in specific group of young and mid-aged patients.

Recommendations for Therapeutic Apheresis by the Section "Preparative and Therapeutic Hemapheresis" of the German Society for Transfusion Medicine and Immunohematology

The section "Preparative and Therapeutic Hemapheresis" of the German Society for Transfusion Medicine and Immunohematology (DGTI) has reviewed the actual literature and updated techniques and indications for evidence-based use of therapeutic apheresis in human disease. The recommendations are mostly in line with the "Guidelines on the Use of Therapeutic Apheresis in Clinical Practice" published by the Writing Committee of the American Society for Apheresis (ASFA) and have been conducted by experts from the DACH (Germany, Austria, Switzerland) region.

Arterial and venous thrombosis by high platelet count and high hematocrit: 108 521 individuals from the Copenhagen General Population Study

BACKGROUND

It is unclear whether high platelet count or high hematocrit predict risk of thrombosis in individuals from the general population.

OBJECTIVES

We tested the hypothesis that individuals from the general population with high platelet count or high hematocrit have high risk of arterial and venous thrombosis.

METHODS

We prospectively followed 108 521 individuals from The Copenhagen General Population Study for a median of 8 years. Platelet count and blood hematocrit were measured at study entry.

RESULTS AND CONCLUSION

Multivariable adjusted hazard ratios for individuals with platelet counts in the top 5 percentiles (>398 × 109 /L) vs in the 25th-75th percentiles (231-316 × 109 /L) were 1.77 (95% confidence interval [CI], 1.38-2.24) for arterial thrombosis in the brain (38 and 26 events/10 000 person-years) and 0.82 (95%, 0.61-1.11) for arterial thrombosis in the heart (23 and 28 events/10 000 person-years). For individuals with hematocrit values in the top 5 percentiles (women/men: >45/>48%) vs the 25th-75th percentiles (women/men: 38.1-42/41.1-45%), hazard ratios were 1.27 (95% CI, 0.91-1.75) for arterial thrombosis in the brain (40 and 26 events/10 000 person-years) and 1.46 (95% CI, 1.06-2.00) for arterial thrombosis in the heart (43 and 25 events/10 000 person-years). Neither high platelet count nor high hematocrit was associated with risk of venous thromboembolism. When excluding individuals with myeloproliferative neoplasia from the main analyses, results on risk of thrombosis were similar. In this prospective study, high platelet counts were associated with 1.8-fold risk of arterial thrombosis in the brain, whereas high hematocrit was associated with 1.5-fold risk of arterial thrombosis in the heart.

Identification of significant geographic clustering of polycythemia vera cases in Montreal, Canada

BACKGROUND

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm associated at times with debilitating symptoms and a significant mortality rate. Understanding the demographics, epidemiology, and geography of this disease may provide further insight into important risk factors associated with its development. The objective of this study was to analyze patient demographics, incidence, and mortality rates, as well as the geographic distribution of PV patients in Canada between 1992 and 2010.

METHODS

This study was achieved by analyzing the Canadian Cancer Registry, Le Registre Québécois du Cancer, and the Canadian Vital Statistics patient databases.

RESULTS

A total of 4645 patients were diagnosed with PV between 1992 and 2010. While the annual incidence rate of this cancer fluctuated in Canada, mortality rate analysis indicated a decreasing trend. Geographically, PV incidence rates were notably elevated in the province of Quebec compared with the Canadian average. Further analysis of high-incidence forward sortation areas indicated a striking clustering of cases in the H4W region encompassing the Côte-Saint-Luc borough of Montreal, with an incidence of 102.97 (95% confidence interval, 75.11-137.79) cases per million per year, which is >13 times the national average.

CONCLUSION

The residential area of Côte-Saint-Luc is an important PV cluster in Canada, with high concentration of retirement homes and geriatric hospices. Also, Jewish residents comprise >60% of the population in this neighborhood. These findings suggest that an older age and, potentially, an inherent genetic predisposition may be implicated in the pathogenesis of this malignancy. This study provides a comprehensive overview of PV burden/geographic distribution of cases in Canada.

Somatic Mutations in Philadelphia Chromosome-Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPN) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). MPN are characterized by clonal proliferation of myeloid progenitors leading to erythrocytosis, thrombocytosis, or leukocytosis, and risk of hemorrhagic and thrombotic events, as well as myelofibrosis and blast transformation. The discovery of somatic mutations in MPN, namely JAK2 V617F, JAK2 exon 12, MPL, and CALR mutations, has permitted a more specific approach to diagnosis and treatment. The prevalence of JAK2 V617F mutations is higher than 95% in PV, 50%-75% in ET and 40%-75% in PMF. JAK2 exon 12 mutations are specific of PV. A 20%-30% of patients with ET and PMF present a CALR mutation. The screening of mutations strengthens the diagnosis of MPN since 97% of MPN have at least 1 somatic mutation. Interestingly, different mutations grant different phenotype and prognosis. Of particular importance, CALR mutations grant a favorable prognosis in ET and PMF, while ASXL1 mutations confer a poorer outcome. In fact, the use of CALR/ASXL1 status for the prognostication of patients has increased clinical value and is now suggested for guidance of therapy in PMF. The increasing importance of mutations in the management of MPN warrants a more frequent revision of current diagnostic criteria and prognostic models and a better understanding of the mechanisms leading to MPN subset differentiation.

Active Smoking and Hematocrit and Fasting Circulating Erythropoietin Concentrations in the General Population

Cigarette smoking continues to be one of the major risk factors for increased morbidity and mortality worldwide. Among many adverse health effects, smoking can induce erythrocytosis, which is commonly believed to result from elevated serum erythropoietin (EPO) levels. Currently, however, this notion is only alleged, without data available to substantiate it. Hence, we analyzed data from the Prevention of Renal and Vascular End-Stage Disease study, a prospective population-based cohort study. Smoking behavior was quantified as number of cigarettes smoked per day and as 24-hour urinary cotinine excretion levels, an objective and quantitative measure of nicotine exposure. In 6808 community-dwelling participants, the prevalence of nonsmokers, former smokers, and current smokers were 29%, 43%, and 28%, respectively. Hematocrit levels were higher in current smokers (41.4%±3.6%) than in nonsmokers (40.3%±3.6%) (P<.001). In contrast, median EPO levels were lower in current smokers (7.5 IU/L; interquartile range [IQR], 5.7-9.6 IU/L) than in nonsmokers (7.9 IU/L; IQR, 6.0-10.7 IU/L) (P<.001). In multivariate linear regression analysis, current smoking, compared with nonsmoking, was independently positively associated with hematocrit levels (β=.12; P<.001) and hemoglobin levels (β=.11; P<.001), but inversely associated with EPO levels (β=-.09; P<.001). In sensitivity analyses, we observed a dose-dependent inverse association of smoking exposure reflected by 24-hour urinary cotinine excretion levels with EPO levels. Contrary to common belief, we identified that in the general population, smoking is inversely associated with EPO levels. Future mechanistic insight is needed to unravel the currently identified association, and if reproduced in other studies, guidelines for diagnosis of secondary erythrocytosis may need to be revisited.

Polycythemia vera masked due to severe iron deficiency anemia

Polycythemia vera is one of the chronic myeloproliferative diseases and very few patients present with its actual clinical manifestations. The most common findings are increased red cell mass and an increased leukocyte count with decreased erythropoietin. We present a case where there was a delay in the diagnosis of polycythemia because of menorrhagia in the past. On admission, the patient presented with elevated red and white blood cell counts, erythropoietin was low, and polycythemia was then suspected. A bcr-abl test was performed to rule out chronic myelogenous leukemia. JAK2 mutation was positive, and the patient was diagnosed with polycythemia vera.

Perioperative blood product administration and thromboembolic events in patients with treated polycythemia vera: a case-control study

BACKGROUND

Patients with polycythemia vera (PV) have historically been considered to be at high risk for perioperative hemorrhagic and thromboembolic complications. However, no recent studies have compared these outcomes between treated PV patients and patients without PV undergoing similar procedures.

STUDY DESIGN AND METHODS

Patients with PV who underwent surgery with anesthesia from June 1, 2006, to May 31, 2011, were randomly matched (sex, age, type of surgical procedure, surgical year) at a ratio of 1:4 with control patients without PV. Conditional logistic regression analysis adjusting for surgical duration, preoperative hemoglobin, platelet count, and cardiovascular disease was used to assess the association between PV and blood product transfusions, thromboembolism, and other major cardiovascular and pulmonary complications.

RESULTS

Fifty-six PV patients who underwent 79 surgeries were matched with 312 controls. During hospitalization, 35 (44.3%) and 82 (25.9%) PV and control patients, respectively, were transfused with blood products. PV patients were at increased risk for transfusion intraoperatively (odds ratio [OR], 4.35; 95% confidence interval [CI], 1.79-10.57; p = 0.001) and during hospitalization (OR, 4.35; 95% CI, 1.84-10.31; p < 0.001). The likelihood of thromboembolic complications and/or other major complications did not differ between the two study groups (thromboembolic-OR 1.53, 95% CI 0.39-6.02, p = 0.540; other major complications-OR 2.15, 95% CI 0.93-4.96, p = 0.073).

CONCLUSIONS

Medically managed PV patients had an increased likelihood of receiving blood products perioperatively. Given the low number of observed thromboembolic events, we cannot make definitive conclusions regarding the association between PV and thromboembolism.

Polycythemia vera presenting as acute myocardial infarction: An unusual presentation

Acute myocardial infarction (AMI) is usually seen in the setting of atherosclerosis and its associated risk factors. Myocardial infarction in the young poses a particular challenge, as the disease is less likely, due to atherosclerosis. We report the case of a 37-year-old female patient who presented with ST segment elevation anterolateral AMI. The only abnormality on routine blood investigation was raised hemoglobin and hematocrit. After further testing, she was diagnosed according to the World Health Organization (WHO) criteria with polycythemia vera. This case illustrates the importance of recognizing polycythemia vera as an important cause of thrombosis, which can present initially as AMI, and to emphasize the early recognition of the disease in order to initiate appropriate management strategies.

Commonly used drugs in hematologic disorders

The drugs used to treat hematologic disorders constitute an extraordinary array of agents and include therapy for anemias, bleeding diatheses, thromboembolism and hematologic malignancies. Within many of these categories, hematologic therapies represent molecular understanding of the disease pathophysiology and a treatment targeted precisely at the known aberration. In this chapter we discuss these treatments, with greater emphasis on the most commonly used agents and the latest advances in the specific field. The chapter includes discussion on old (cyclooxygenase inhibitors) and new antiplatelet agents (ADP receptor P2Y12 inhibitors), newly described oral thrombin inhibitors such as dabigatran, treatment targeted at the bcr-abl tyrosine kinase in chronic myeloid leukemia and demethylating agents in myelodysplasia. The discussion is also oriented towards neurologic implications, both therapeutic and toxic, for each therapy or therapeutic group.

Sensomotor axonal peripheral neuropathy as a first complication of polycythemia rubra vera: A report of 3 cases

Patient: Female, 64

Final Diagnosis: Polycythemia rubra vera

Symptoms: Burning pain • cramps • hypesthesia • itching • paresthesia

Medication: —

Clinical Procedure: —

Specialty: Neurology

Simple paper-based test for measuring blood hemoglobin concentration in resource-limited settings

BACKGROUND

The measurement of hemoglobin concentration ([Hb]) is performed routinely as a part of a complete blood cell count to evaluate the oxygen-carrying capacity of blood. Devices currently available to physicians and clinical laboratories for measuring [Hb] are accurate, operate on small samples, and provide results rapidly, but may be prohibitively expensive for resource-limited settings. The unavailability of accurate but inexpensive diagnostic tools often precludes proper diagnosis of anemia in low-income developing countries. Therefore, we developed a simple paper-based assay for measuring [Hb].

METHODS

A 20-μL droplet of a mixture of blood and Drabkin reagent was deposited onto patterned chromatography paper. The resulting blood stain was digitized with a portable scanner and analyzed. The mean color intensity of the blood stain was used to quantify [Hb]. We compared the performance of the paper-based Hb assay with a hematology analyzer (comparison method) using blood samples from 54 subjects.

RESULTS

The values of [Hb] measured by the paper-based assay and the comparison method were highly correlated (R(2) = 0.9598); the standard deviation of the difference between the two measurements was 0.62 g/dL. The assay was accurate within 1 g/dL 90.7% of the time, overestimating [Hb] by ≥1 g/dL in 1.9% and underestimating [Hb] by ≥1 g/dL in 7.4% of the subjects.

CONCLUSIONS

This study demonstrates the feasibility of the paper-based Hb assay. This simple, low-cost test should be useful for diagnosing anemia in resource-limited settings, particularly in the context of care for malaria, HIV, and sickle cell disease patients in sub-Saharan Africa.

Thrombosis in myeloproliferative neoplasms with JAK2V617F mutation

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders and are characterized by advanced proliferation and survival advantage. These abnormalities are considered to derive from the point mutation in exon 14 of the Janus kinase 2 genes (JAK2 V617F). The thrombosis rate and the high prevalence of JAK2V617F in patients with MPN suggest that there is an association between the 2 in MPN. Apart from the mutation, other variables are documented to cause endothelial dysfunction and involve in thrombotic tendency. Endothelial progenitor cells differentiated from hematopoietic stem cell in patients with JAK2V617F MPN play an indispensable role in initiating and modulating neoangiogenesis. Although a risk-oriented therapeutic approach has been applied to MPN treatments, the further study on pathogenesis of MPN may provide more novel preventions and therapies for MPN.

Polycythemia and chorea

Polycythemia vera is a sporadic myeloproliferative disorder of increased red blood cell mass affecting multiple organ systems. Associated thrombosis, hemorrhaging, and hyperviscosity commonly result in neurological manifestations, sometimes in the form of chorea and ballism. Resultant choreiform movements have been mainly described as generalized with orofaciolingual and appendicular muscle involvement, hypotonia, and hyporeflexia. Chorea has also been uncommonly reported as arising from secondary causes of polycythemia; however, the underlying pathophysiology has not been clearly elucidated. Proposed mechanisms for basal ganglia dysfunction include hypoperfusion due to venous stasis, receptor hypersensitivity in a setting of reduced catecholamine levels, and altered platelet dopamine metabolism. Magnetic resonance imaging and single-photon emission computed tomography perfusion studies have failed to reveal an anatomical or physiological basis for polycythemia vera-associated chorea, yet rare pathological examinations of deceased patients have shown signs of cerebral venous thrombosis and perivenous demyelination. Administration of neuroleptics may suppress abnormal choreiform movement; however, effective management of polycythemia vera requires serial venesections in conjunction with chemotherapy. Appropriate treatment may prolong survival to more than 10 years, although chorea may spontaneously remit, re-emerge with resurgence of disease, or continue indefinitely despite maintenance therapy.

Hydroxyurea: The drug of choice for polycythemia vera and essential thrombocythemia

Hydroxyurea is an old drug that is often used to control essential thrombocythemia and polycythemia vera in patients with high-risk disease. It is usually well tolerated and cheap and has been proven effective in many studies for the prevention of thrombohemorrhagic complications associated with these disorders. However, many clinicians are reluctant to use it because of the perceived risk of progression to acute leukemia. Several recent, large studies have given this drug a new lease on life. Relevant results from these studies are discussed, and the risk of leukemia is placed in perspective to demonstrate that hydroxyurea remains the drug of choice in patients with either of these disorders.

A multidisciplinary investigation of a polycythemia vera cancer cluster of unknown origin

Cancer cluster investigations rarely receive significant public health resource allocations due to numerous inherent challenges and the limited success of past efforts. In 2008, a cluster of polycythemia vera, a rare blood cancer with unknown etiology, was identified in northeast Pennsylvania. A multidisciplinary group of federal and state agencies, academic institutions, and local healthcare providers subsequently developed a multifaceted research portfolio designed to better understand the cause of the cluster. This research agenda represents a unique and important opportunity to demonstrate that cancer cluster investigations can produce desirable public health and scientific outcomes when necessary resources are available.

Splenectomy normalizes hematocrit in murine polycythemia vera

Splenic enlargement (splenomegaly) develops in numerous disease states, although a specific pathogenic role for the spleen has rarely been described. In polycythemia vera (PV), an activating mutation in Janus kinase 2 (JAK2^V617) induces splenomegaly and an increase in hematocrit. Splenectomy is sparingly performed in patients with PV, however, due to surgical complications. Thus, the role of the spleen in the pathogenesis of human PV remains unknown. We specifically tested the role of the spleen in the pathogenesis of PV by performing either sham (SH) or splenectomy (SPL) surgeries in a murine model of JAK2^V617F-driven PV. Compared to SH-operated mice, which rapidly develop high hematocrits after JAK2^V617F transplantation, SPL mice completely fail to develop this phenotype. Disease burden (JAK2^V617) is equivalent in the bone marrow of SH and SPL mice, however, and both groups develop fibrosis and osteosclerosis. If SPL is performed after PV is established, hematocrit rapidly declines to normal even though myelofibrosis and osteosclerosis again develop independently in the bone marrow. In contrast, SPL only blunts hematocrit elevation in secondary, erythropoietin-induced polycythemia. We conclude that the spleen is required for an elevated hematocrit in murine, JAK2^V617F-driven PV, and propose that this phenotype of PV may require a specific interaction between mutant cells and the spleen.

A critical review of anagrelide therapy in essential thrombocythemia and related disorders

Thrombocytosis is a common clinical problem and it represents either a primary myeloid disorder (a clonal process) or a reactive phenomenon. While reactive thrombocytosis is often inconsequential, clonal thrombocytosis may require cytoreductive therapy to prevent thrombohemorrhagic complications. In this regard, a controlled clinical trial has previously demonstrated the efficacy of hydroxyurea in reducing the risk of thrombosis in high-risk patients with essential thrombocythemia (ET). Despite the absence of similar evidence for clinical benefit, the platelet-lowering agent anagrelide has been widely used in both ET and polycythemia vera (PV) and recent reports of serious side-effects suggest that such practice might be detrimental to patients. In the current review we provide basic drug information as well as a critical assessment of anagrelide treatment in ET and related disorders.

Essential thrombocythemia, polycythemia vera, and myelofibrosis: current management and the prospect of targeted therapy

The recent discovery of JAK2 and/or MPL mutations in polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) has had a major impact on how we diagnose and treat these disorders. For instance, the presence of a JAK2 mutation is now considered conditio sine qua non for the diagnosis of PV and the World Health Organization classification system has recently revised its diagnostic criteria for PV, ET, and PMF to include JAK2 and MPL mutations as clonal markers. From the standpoint of treatment, JAK-STAT is now identified as a legitimate target pathway for drug development in myeloproliferative neoplasms. Herein, I will first outline my views regarding current management in ET, PV, and PMF and then discuss emerging data on preclinical and clinical activity of anti-JAK2 small molecule drugs. Am. J. Hematol., 2008. (c) 2008 Wiley-Liss, Inc.

Cytogenetic and molecular aspects of Philadelphia negative chronic myeloproliferative disorders: clinical implications

Chronic myeloproliferative disorders (CMPD) are clonal disorders of the hematopoietic stem cell. The myeloid lineage shows increased proliferation with effective maturation, while peripheral leukocytosis, thrombocytosis or elevated red blood cell mass are found. In Philadelphia negative CMPD recurrent cytogenetic abnormalities occur, but no specific abnormality has been defined to date. The spectrum of cytogenetic aberrations is heterogeneous ranging from numerical gains and losses to structural changes including unbalanced translocations. The most common chromosomal abnormalities are 20q-, 13q-, 12p-, +8, +9, partial duplication of 1q, balanced translocations involving 8p11 and gains in 9p. Cytogenetic analysis of CMPD by conventional or molecular techniques has an important role in establishing the diagnosis of a malignant disease, adding also more information for disease outcome. Molecular studies may detect the possible role of candidate genes implicated in the neoplastic process, addressing new molecular target therapies. FIP1L1/PDGFRalpha rearrangements, as well as alterations of PDGFRbeta or FGFR1 gene have been found to be associated with specific types of CMPD. Recently, a novel somatic mutation, JAK2V617F, has been reported in most of the polycthemia vera (PV) patients, as well as in a lower percentage in essential thrombocythemia (ET) or idiopathic myelofibrosis (IMF) patients. This finding represents the most important advance in understanding of the molecular mechanisms underlined the pathogenesis of CMPD, contributing to the classification and management of patients.