Clinical Manifestation of Calreticulin Gene Mutations in Essential Thrombocythemia without Janus Kinase 2 and MPL Mutations: A Chinese Cohort Clinical Study

Frequency of JAK2V617F, MPL and CALR driver mutations and associated clinical characteristics in a Norwegian patient cohort with myeloproliferative neoplasms

Myeloproliferative neoplasms are hematological disorders characterized by increased production in one or more myeloid cell lines, associated with driver mutations in JAK2-, MPL- and CALR-genes. The aims of this study were to investigate the prevalence of these driver mutations in a Norwegian patient cohort with myeloproliferative neoplasms, and to assess whether the different mutations were associated with different clinical presentation and natural history.Results from 820 patients in whom analysis for JAK2V617F-, CALR- and MPL had been performed at Haukeland University Hospital in the period 2014-2019 were retrieved and analyzed together with clinical variables related to diagnosis, hematological blood parameters and complications, obtained from patient records.We identified 182 cases of myeloproliferative neoplasms: 78 with JAK2V617F, 28 with CALR-mutations, two with MPL-mutations and 23 cases without a driver mutation. There was a lower prevalence of JAK2V617F mutation than expected in the polycythemia vera group, likely related to overdiagnosis. In patients with essential thrombocytosis, we found significantly higher levels of hemoglobin and erythrocyte volume fraction for JAK2V617F-mutated disease, and significantly higher levels of platelets and lactate dehydrogenase for CALR-mutated disease. Patients with JAK2V617F-mutated primary myelofibrosis had significantly higher levels of hemoglobin, and there was an increased number of smokers or former smokers in this group compared to patients with CALR-mutations.Except for a lower prevalence of JAK2V617F-mutation in polycythemia vera, the mutational distribution in our patient cohort was similar to previous findings in other populations. The novel finding of a higher prevalence of smokers in JAK2V617F-mutated primary myelofibrosis warrants further investigation.

Hematological relevance of JAK2 V617F and calreticulin mutations in Tunisian patients with essential thrombocythemia

Background

The genetic investigation of essential thrombocythemia(ET) has highlighted the presence of driver mutations in ET. Janus kinase JAK2V617F and calreticulin(CALR) mutations are the most frequent driver mutations and have significantly improved the molecular diagnosis of ET. The impact of genetic heterogeneity on clinical features has not been fully elucidated.

This is the first study which aimed to determine the frequency of JAK2V617F and CALR exon9 mutations in Tunisian ET patients and to establish the correlation between hematological characteristics and mutational status.

Methods

This study included Tunisian patients suspected with ET and was conducted between September 2017 and March 2021. Genomic DNA of patients was isolated from peripheral blood samples. JAK2V617F was detected by AS‐PCR and CALR mutations were detected by PCR/direct sequencing. Clinical and hematological characteristics were also analyzed.

Results

Two hundred and fifty ET patients were enrolled in this study. JAK2V617F mutation was found in 166/250 (66.4%) of patients, whereas CALR mutations were detected in 27/84 (32.1%) patients without JAK2V617F. Compared with JAK2V617F‐positive patients, those with CALR mutations showed lower hemoglobin level and lower leucocytes count (p = 0.007 and p = 0.004,respectively). CALR type 2 was the most frequent mutation of CALR detected in 55.55% of CALR mutated. Six of seven patients with thrombotic events harbored JAK2V617F mutation.

Conclusion

The prevalence of driver mutations JAK2V617F or CALR mutations was 77.2% in Tunisian ET patients. Moreover, patients with JAK2 V617F mutation had a higher risk of thrombosis. The mutational status is necessary to improve the diagnosis and contribute to the therapeutic decisions.

JAK2V617F, CALR and MPL515L/K mutations and plateletcrit in essential thrombocythemia: A single centre's experience

AIMS

JAK2V617F (JAK2), calreticulin (CALR) and MPL515L/K (MPL) mutations are important in essential thrombocythemia (ET) and may be associated with various clinical consequences of the disease. This study aimed to compare the clinical and haematological parameters of ET patients regarding the mentioned mutations and the role of plateletcrit (PCT).

METHODS

Seventy patients who were diagnosed with ET between 2005 and 2017 in a single centre were included in this descriptive study. The initial symptoms and clinical findings were retrieved from the electronic database. JAK2 gene V617F mutations, MPL gene exon 10 mutations and CALR gene exon 9 DNA sequence analyses were performed. Forty-one healthy volunteers were included to perform ROC curve analysis for interpreting PCT value.

RESULTS

The distributions of patients according to the mutations were as follows: Thirty-seven (52.9%) patients were JAK2-positive, 15 (21.4%) were CALR-positive, 2 (2.8%) patients were positive for both CALR and JAK2, and 1 (1.4%) was only MPL-positive. Fifteen (21.4%) patients were triple-negative. The ET patients with JAK2 mutation showed a higher level of haemoglobin at the time of diagnosis. The ET patients with CALR mutation presented with higher platelet and LDH levels (P = .002 and P = .001, respectively). The PCT level was higher in the CALR-positive group when compared to the others (P = .026). A sensitivity value of 97.6% and specificity value of 98.6% were determined regarding PCT% at a cut-off value of 0.37 in ET patients. In CALR-positive patients, the sensitivity and specificity values were 100% for the PCT at a cut-off value of 0.42%.

CONCLUSION

We determined that the platelet count and blood LDH level was high in the ET patient group with CALR mutation. Besides, we found that the blood haemoglobin level was higher in the ET patient group with JAK2 mutation. Additionally, the PCT level was higher in the CALR group when compared to the other patient groups.

A novel biomarker of chronic allograft dysfunction in renal transplant recipients (serum calreticulin and CD47)

Background

Chronic allograft dysfunction (CAD) is considered the leading cause of late allograft loss. The cluster of differentiation 47 (CD47) and calreticulin (CRT) are involved in many and diverse cellular processes. The present study was designed to study the role of the pro-phagocytic CRT and anti-phagocytic CD47 signals in patients with renal transplantation in relation to graft function.

Thirty renal transplantation recipients (RTR) for more than 6 months [15 with stable renal function and 15 with chronic allograft dysfunction (CAD)] and 15 healthy controls were enrolled in the study. Quantification of CRT, CD47, and high-sensitivity C-reactive protein (hsCRP) levels in serum was done using standardized enzyme-linked immunosorbent assay (ELISA) kits. Measurement of renal function and urinary alkaline phosphatase (U.ALP) was done. Renal interstitial fibrosis (IF) was graded in renal biopsies of CAD.

Results

Serum CRT and urinary ALP levels were statistically significant higher (P < 0.001) while serum CD47 level was statistically significant lower (P < 0.001) in patients with CAD than patients with stable graft function and controls. There was statistically insignificant difference between controls and patients with stable graft function. Serum CRT and serum CD47 levels were positively correlated with each other and with worsening renal and tubular function, serum hsCRP in RTR and with degree of renal IF in patients with CAD (P < 0.05).

Conclusions

The activation and dysregulation of CRT and CD47 could play a role in the development of CAD and could be a potential biomarker for renal allograft dysfunction.

[Risk factors for recurrent thrombosis in patients with polycythemia vera and essential thrombocythemia]

Objective: To analyze the clinical characteristics of recurrent thrombosis in patients with polycythemia vera (PV) and essential thrombocythemia (ET) to probe the risk factors for recurrent thrombosis in patients with ET and PV. Methods: The clinical data of 104 ET and PV patients with thrombosis in Beijing Anzhen Hospital from February 2001 to November 2016 were retrospectively analyzed. Thrombosis reoccurred in 38 patients. Statistical analyses were performed by multivariate logistic regression for risk factors of recurrent thrombosis in ET and PV patients. Results: Recurrent thrombosis occurred in 36.5% of patients with ET/PV, the total incidence rate in ET and PV patients was 9.8% patient-years, 12.3% patient-years and 5.7% patient-years in ET and PV respectively. There were a total of 56 re-thrombotic events, and 42.1% of events occurred within 1 year after the first thrombosis. The arterial re-thrombosis was 97.4% (most of acute coronary syndrome, ACS), and venous events was 2.6%. The most common cases of re-thrombosis were ACS in ET patients (18 cases, 64.3%), and cerebral infarction in PV patients (7 cases, 70.0%). The number of PV patients with 2 times or more re-thrombotic events was significantly higher than that of ET patients (9 cases, 90.0% vs 7 cases, 25.0%). The proportion of the patients with WBC>12.5×10(9)/L or Hct>45%, and thrombosis history or splenomegaly and high risk thrombotic events were higher than those with a single thrombus (52.6% vs 31.8%; 50.0% vs 30.0%; 86.8% vs 13.6%; 84.2% vs 33.3%; 52.6% vs 15.2%; 94.7% vs 53.0%; P values were 0.036,0.046, <0.001, <0.001, <0.001 and <0.001, respectively). Logistic regression analysis showed that thrombosis history (OR=13.697, P=0.025), splenomegaly (OR=13.301, P=0.034) and high risk stratification of thrombotic events (OR=44.618, P=0.025) were independent risk factors for recurrent thrombotic events. Conclusions: ET and PV patients had a higher risk of re-thrombosis. The incidence of re-thrombosis in ET was higher than in PV, ACS was more common cases of re-thrombotic events; but PV patients were more susceptible to multiple re-thromboses than ET ones, also with more cerebral infarction. Previous thrombus history, splenomegaly and high risk stratification of thrombotic events were independent risk predictors for re-thrombosis of ET and PV patients.

Assessing the thrombotic risk of patients with essential thrombocythemia in the genomic era

The molecular characterization of myeloproliferative neoplasms, including essential thrombocythemia (ET), has enabled deeper understanding of their pathogenesis. A driver lesion, namely, Janus kinase (JAK)2V617F, calreticulin (CALR) or myeloproliferative leukemia (MPL) gene mutation can be identified in the vast majority of patients. Each of these mutations is associated with distinct clinical features and may modulate the patients' clinical course, risk of complications, including vascular events, and survival. JAK2V617F appears to be a risk-modifying mutation and has been shown to increase the likelihood of thrombotic events in patients with ET across studies. As such, it has been included in prognostic models and its presence may influence treatment decisions. The association of CALR and MPL mutations with the incidence of vascular events has been less clear. Even more limited information is available on the contribution of additional non-driver lesions to the thrombotic risk. In this review we discuss the available evidence on the role of recurrent mutations in the risk of thrombotic complications in patients with ET and how these mutations weigh into modern prognostic scores.