Succinate dehydrogenase deficient (SDH-deficient) gastrointestinal stromal tumors (GISTs), as defined by the expression loss of the subunit B of the succinate dehydrogenase complex, account for approximately 20% to 40% of all KIT/PDGFRA wild-type (WT) GISTs and 5% of all GISTs [1]. The gene discussed is KIT; the disease is gastrointestinal stromal tumor.