Frequency of JAK2V617F and CALR somatic mutations in Egyptian patients with thrombocytosis: relation with clinical and hematological phenotype

Background Thrombocytosis has a multitude of potential etiologies: spurious, reactive, and clonal. Clonal thrombocytosis carries a greater risk of thrombosis than reactive causes. Therefore, careful distinction between the causes of thrombocytosis is important and challenging as it carries implications for evaluation, prognosis, and treatment strategies. Aim of the work To determine the frequency of JAK2V617F and calreticulin (CALR) somatic mutations in patients with thrombocytsis and their relation with clinical and hematological phenotype. Patients and methods A total of 50 BCR-ABL-negative patients with persistent thrombocytosis were tested for both JAK2V617F mutation by real-time polymerase-chain reaction (RT-PCR) and CALR exon-9 mutation by high-resolution melting PCR. Results JAK2V615F mutation was detected in 17 (34%), whereas CALR exon-9 mutation was detected in 10 (20%) out of the 50 studied patients with thrombocytosis. One patient with essential thrombocythemia was heterozygous for both mutations. The incidence of JAK2V615F mutation was significantly higher in males (P=0.007), with higher mean age (P=0.001), higher incidence of thrombosis (0.034), and leukocytosis (0.035) compared with CALR and dual-negative mutations. Meanwhile, anemia (P=0.001), platelets (P=0.009), and lactate dehydrogenase (P=0.009) were significantly higher in CALR-mutated patients. Conclusion Both JAK2 and CALR somatic mutations were detected in 52% of patients with thrombocytosis. CALR-mutated cases show clinical and hematological phenotype different from JAKV617F-positive ones and might be considered as a distinct disease entity with more indolent course.