Activating mutations of the tyrosine kinase receptor KIT have been described in both mastocytosis and gastrointestinal stromal tumors (GIST), but are usually found in separate domains and often respond differently to signal transduction inhibitors.
Mastocytosis is a disorder resulting from an abnormal mast cell (MC) accumulation in tissues that is often associated with the D816V mutation in KIT, the tyrosine kinase receptor for stem cell factor.
Primary disorders causing constitutively hyperactivity of mast cells are called mastocytosis and are frequently due to a gain-of-function mutation of the KIT gene encoding the transmembrane tyrosine kinase receptor.
Together with enhanced NT levels, the elevated expression of modified Trk receptors on skin and gut MCs might contribute to the pathophysiology of mastocytosis in autocrine and paracrine loops.
The proto-oncogene C-KIT encodes a tyrosine kinase receptor that is expressed on mast cells and haematopoietic stem cells and can show somatic mutations in patients with mastocytosis.