Inherited predisposition to PCC/PGL is associated with constitutional pathogenic variants (PVs) in >15 genes, including SDHA, SDHAF2, SDHB, SDHC, SDHD, VHL, FH, MAX, TMEM127, RET, MEN1, and NF1. 4,7 Among the Mendelian PCC/PGL cases, the most sizable contribution is from PVs in SDHB followed by SDHD. 4,8 Associations with subphenotypes of head-and-neck paragangliomas, namely multiple, familial, and/or young-onset disease, have been reported with underlying germline PVs in SDHA, SDHB, SDHC or SDHD (SDHx) and with metastatic disease for SDHB PVs.9 This evidence concerns the gene SDHD and adrenal gland pheochromocytoma.