The clinical criterion for the diagnosis of MEN1 is the presence of two of the three major neuroendocrine tumor (NET) types in an index patient, i.e., tumors of the parathyroid, pituitary, and/or pancreatic islet cells, or a MEN1-associated tumor in a family member of a patient with MEN1 [1]. This evidence concerns the gene MEN1 and neoplasm.