On the other hand, SDH mutations cause intra-adrenal tumours less commonly; 25% of SDHB-related tumours are phaeochromocytomas while the frequency of intra-adrenal tumours in SDHD, SDHA and SDHC are even lower (4,7,36,37,41,53). This evidence concerns the gene SDHB and pheochromocytoma.