In addition to those patients who harbor a mutation in SDHB, other established risk factors for metastatic disease include tumor size ≥ 5 cm, extra-adrenal PGL, dopaminergic phenotype (plasma 3-methoxytyramine higher than three times the URL), and a Ki-67 index > 3% (3, 26). The gene discussed is SDHB; the disease is neoplasm.