The FLT3-ITD mutation is by far the most common of the two common mutations of FLT3, and when present at a high variant allele frequency (often measured as high >0.5 FLT3-ITD allelic ratio) in the entire leukemia clonal population, it promotes a more aggressive disease phenotype and poor prognosis [2,3]. This evidence concerns the gene FLT3 and leukemia.