Patients with RTK-wild type GIST (including SDH-deficient as well as SDH-competent GIST) have lower IM response rates compared to KIT exon 11 mutant GIST [9, 10], although sunitinib response rates have been higher for RTK-wild type GIST [64]. The gene discussed is SDHB; the disease is gastrointestinal stromal tumor.