In conclusion, next-generation sequencing of an SDH-intact, KIT, PDGFR, BRAF wild type GIST identified for the first time somatic loss of function mutations in two tumor-suppressor genes, NF1 and MAX. Somatic inactivation of neurofibromin should be explored as a potential oncogenic mechanism in this subset of GIST. The gene discussed is SDHB; the disease is gastrointestinal stromal tumor.