Kit Mutations: New Insights and Diagnostic Value

Mastocytosis is a World Health Organization–defined clonal mast cell disorder characterized by significant clinicopathologic heterogeneity. Despite this diversity, a mutation of the KIT gene, most commonly D816V, is found in almost all cases and believed a driver lesion. Peripheral blood allele–specific oligonucleotide polymerase chain reaction can reliably detect KIT D816V and is used for the initial screening of adults with suspected systemic mastocytosis. The discovery of KIT mutations as central to the pathobiology of mastocytosis has prompted development of KIT-targeted agents, including imatinib and midostaurin (approved medications for patients with advanced systemic mastocytosis), and drugs in development, like KIT D816V–specific inhibitor avapritinib.