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

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).

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.

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%.

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.