Test Details: Most GISTs characteristically express the KIT receptor tyrosine kinase and approximately 80% harbor oncogenic mutations within the KIT gene. These primarily involve KIT exon 11, but may also occur in exons 9, 13 and 17. The four tested exons encompass the majority of mutations found in gastrointestinal stromal tumors (GIST), melanoma, core-binding factor AML (CBF-AML), mast cell disease (systemic mastocytosis) and germ cell tumors. Mutation identification is useful for planning TKI therapy and predicting clinical course.