Germline mutations in the MEN1 gene lead to MEN1 syndrome, characterized by various types of endocrine and non-endocrine tumors, including pituitary adenomas, hyperplastic parathyroids, and neuroendocrine pancreatic tumors, with a high penetrance of disease but PCC/PGL are rare and account for <1% of PCC/PGL [64,65,66]. This evidence concerns the gene MEN1 and adrenal gland pheochromocytoma.