FLT3 ITDs. This diagram illustrates how FLT3 mutations can be defined as “juxtamembrane insertion” and “kinase domain insertion.” For the large majority of FLT3-ITD mutations, the duplicated sequence includes the codon for residue arginine 595 (R595).²⁹  The resultant amino acid sequence inserted typically ranges from 3 to 42 residues. When the insertion is short, it consists only of juxtamembrane sequence, whereas longer duplications include residues from the kinase 1 domain. Therefore, in the case of these longer insertions, the actual duplicated sequence begins within that kinase domain and are sometimes referred to as a kinase domain insertion. Professional illustration by Somersault18:24.