FLT3 and acute promyelocytic leukemia: At the molecular level, the result of the t(15;17) is the formation of two functional fusion genes, PML-RARα and RARα-PML on the derivative chromosomes 15 and 17 respectively.5,8,9,16 A variety of PML-RARα transcripts [bcr1 or Long (L), bcr3 or Short (S), bcr2 or Variable (V)] are produced due to different breakpoints in PML gene and alternative splicing in chromosome 15.17,18 The FLT3 gene aberrations, including internal tandem duplications (ITDs) and D835 (tyrosine kinase domain, TKD) mutations occur in 30%–50% in APL.