In a study of 173 patients with pheochromocytoma and/or paraganglioma, all patients with MEN2 and NF1 mutations had elevated plasma metanephrine, whereas patients with VHL mutations usually had elevated normetanephrine, and 70% of patients with SDHB and SDHD mutations had elevated plasma methoxytyramine. Here, SDHD is linked to hereditary pheochromocytoma-paraganglioma.