Objective: To determine the frequency of JAK2V617F mutation in Thai patients with clinically suspected myeloproliferative neoplasms [MPNs] including polycythemia vera [PV], essential thrombocythemia [ET], primary myelofibrosis [PMF] and unclassified MPN.

Materials and Methods: Overall, 1,247 samples were tested for JAK2V617F from January 2009 to May 2016. DNA was extracted from leukocytes separated from peripheral blood or bone marrow. JAK2V617F was detected by allele specific polymerase chain reaction [AS-PCR] followed by agarose gel electrophoresis analysis.

Results: The proportion of JAK2V617F positivity in disease subtypes was 49% for suspected PV, 54% for suspected ET, 43% for suspected PMF and 45% for unclassified MPN. The presence of JAK2V617F in each disease subtype was associated with a significant overproduction of the blood compartments including increased leukocyte counts (p<0.001) and platelet counts in PV (p<0.001), increased leukocyte counts (p<0.001), hemoglobin levels (p<0.001) and hematocrits in ET (p<0.001), and increased platelet counts in PMF (p = 0.023) as compared to JAK2-wild type.

Conclusion: JAK2V617F was present in approximately half of the test samples with a high clinical suspicion of various types of MPNs. The prevalence of JAK2V617F in clinically suspected PV cases
was much lower than expected.

Keywords: Myeloproliferative neoplasms; JAK2V617F mutation; Allele specific PCR; Polycythemia, Thrombocythemia