Specific genotype–phenotype correlations have emerged for patients with germline SDHx mutations; SDHB variants are most commonly associated with RCC SDHD with head and neck paragangliomas and SDHA with GIST.8 23 24 The underlying shared mechanism of tumourigenesis for SDHx mutated tumours includes a complex interplay between succinate metabolism, metabolic reprogramming, redox imbalance and epigenetic regulation. The gene discussed is SDHB; the disease is gastrointestinal stromal tumor.