Approximately 50-60% of the oncogenic mutations in Gastrointestinal stromal tumors (GIST) are present in Exon 11 of the KIT gene. The E554K variant is present in Exon 11 of the KIT gene. Identification of GIST genotype is important given the availability of targeted therapy with KIT/PDGFRA tyrosine kinase inhibitors (eg, imatinib, sunitinib, etc).