Journal of the Medical Association of Thailand Vol 104, No 5:MAY 2021 0125-2208 104 5 2021 May JAK2, CALR, MPL, and ASXL1 Mutations in 136 Thai Patients with Philadelphia-Negative Myeloproliferative Neoplasms and Their Correlations with Clinical Outcomes 834-45 EN Dollapak Apipongrat Tontanai Numbenjapon Thirayost Nimmanon Pasra Arnutti Original Article To investigate these mutations in Thai Ph-negative MPN patients. One hundred thirty-six MPN (48 PV, 72 ET, and 16 PMF) cases were enrolled. Mutations of JAK2 V617F and MPL W515L/K mutations were investigated using allele-specific PCR (AS-PCR) and confirmed by sequencing. CALR and ASXL1 mutations were investigated using Sanger sequencing. The JAK2 V617F mutation was detected in 83.3% of PV, 66.6% of ET, and 50.0% of PMF, and correlated with higher RBC, WBC, and PLT counts in PV. CALR mutations were detected in 16.7% of ET and 12.5% of PMF and associated with a higher PLT count in ET. The MPL W515L mutation was detected in one PMF patient. ASXL1 mutations were detected in 6.3% of PV, 8.3% of ET, and 12.4% of PMF, with c.1954G>A being the preponderant mutational form. ASXL1 mutations increased the risk (RR 27.6) and accelerated the onset of AML transformation. The present study provided the prevalence and clinical correlation of JAK2, CALR, MPL, and ASXL1 mutations among Thai Ph-negative MPN patients. The association of ASXL1 mutations with adverse clinical outcomes suggested the potential usefulness of these mutations as a prognostic marker for Ph-negative MPN patients. JAK2 MPL CALR ASXL1 Thai Philadelphia-negative myeloproliferative neoplasm (MPN)DOI: doi.org/10.35755/jmedassocthai.2021.05.12344Received 22 December 2020 | Revised 11 March 2021 | Accepted 12 March 2021