The receptor is presented under its monomeric form, whereas its wild-type counterpart dimerizes upon ligation with SCF before being activated in normal cells. In children,he KIT D816V PTD mutant (in red) is found in nearly 30% of the patients, whereas the ECD mutants (in blue) are found in nearly 40% of the affected children. In adults, depending of the categoty of mastocytosis, the KIT D81V mutant is found in at least 80% of all patients. The complete list of KIT mutants retrieved in the literature for mastocytosis is depicted here. In children, the structure of KIT is found WT in around 25% of the patients analyzed, whereas in adults, KIT is found WT in less than 20% of all patients analyzed so far. Some of the mutations (in black) are found only in a very few number of patients. Del: deletion; ECD: Extracellular domain; Ins: Insertion; ITD: Internal tandem duplication; JMD: Juxtamembrane domain; KI: Kinase insert; PTD: phosphotransferase domain; TMD: Transmembrane domain. ±: mutation found in less than 1% of the patients; +: mutation found in 1 to 5% of the patients; ++: mutation found in around 30% of pediatric patients and in > 80% of all adult patients.