The FMS – like tyrosine gene (FLT3) is the only formula that codes for the tyrosine kinase group which is a receptor or a signal line transmembrane protein. An FLT3 mutation consisting of internal tandem duplication is the most common form of mutation with FLT3. This form of mutation carries out the duplication of the DNA that belongs to exons 14 or 15. Therefore, in some cases or results, FLT3 behaves or acts like an adverse prognostic indicator. The activation loop of FLT3 is a home to the codon of an aspartate residue. This point is the second most common form of mutation. Almost all results reveal that both forms of FLT3 mutations induce a constitution activation of FLT3.