Of these 32 patients, 71.8% had primary extra-adrenal tumors with genetic analysis demonstrating germline SDHB mutations in 71.9% of patients, SDHD mutations in 9.4% of patients (found in all patients with head and neck paraganglioma), and VHL mutations in 6.3% of patients [72]. Here, SDHD is linked to head and neck paraganglioma.