SDHB and gastrointestinal stromal tumor: Indeed, in half of patients with deficient SDH complexes, the trigger of the GIST is a germline-inactivating (“loss of function”) mutation of a gene encoding one of the SDH subunits (typically a germline SDHA mutation) in combination with a somatic mutation (“frameshift” deletion with stop codon, “missense”, “nonsense”, and “splice site” mutations) [16,46].