ATRX and pheochromocytoma: Interestingly, in neuroendocrine tumors, ATRX abnormalities seem to predict malignant tumor phenotype, being present in high-grade malignant tumors such as neuroblastoma (24), or associated with poor prognosis and/or metastatic potential, such as in pancreatic NET (27), and pheochromocytomas/paraganglioma (26).