In addition, to the tyrosine kinase domain (exons 17 and 18; e.g., D820G or N8221/K), at least 30 different KIT mutations have been identified in the extracellular (exon 8–9), transmembrane (exon 19; e.g., F522C) and juxtamembrane domains (exon 11; e.g., V560 G/I) in a small percentage of mastocytosis patients [106–109]. Here, KIT is linked to mastocytosis.