SDHB and pheochromocytoma: SDHA likely pathogenic or pathogenic germline variants (ie, class 4 or class 5 variants according to ACMG/AMP criteria and henceforth collectively referred to as PGVs) are identified in up to 10% of patients with phaeochromocytoma and paraganglioma (PPGL) and can account for up to 50% of SDH-deficient wild-type gastrointestinal stromal tumours (wtGISTs) or up to 30% of wtGIST.1 wtGIST are a unique and uncommon subtype of GISTs that lack somatic-activating variants in the tyrosine kinase c-KIT or platelet-derived growth factor receptor alpha receptors.