FLT3 mutation and expression did not adversely affect clinical outcome of childhood acute leukaemia-a study of 531 Southeast Asian children by the Ma-Spore study group

FMS‐like tyrosine kinase 3 (FLT3) is critical for normal haematopoiesis and have been reported to be expressed in the majority of acute myeloid and lymphoid malignancies. We correlated the impact of FLT3 mutations and its expression with age, WHO 2008 classification and treatment outcome in 531 childhood acute leukaemias. Of 150 acute myeloid leukaemia (AMLs), 18 (12%) harboured FLT3‐ITD while nine (6%) had FLT3‐TKD. FLT3‐ITD and ‐TKD were rare in acute megakaryoblastic leukaemia (AMKL; FLT3‐ITD 0/26, FLT3‐TKD 1/26) and children below 3 years (n = 2/48). Acute promyelocytic leukaemia (APL) with t(15;17);PML‐RARα (n = 7/18; 39%) harboured the highest frequency of FLT3 mutations, followed by myelomonocytic (n = 4/18; 22%) and AML with t(8;21);RUNX1‐RUNX1T1 (n = 2/21; 9%). FLT3 expression levels were also lowest in AMKL, both in Down's and non‐Down's (p = 0.002) followed by patients