Interestingly, only a small percentage of sporadic pituitary tumors harbor mutations in the genes implicated in familial pituitary tumor disorders [MEN1, Cyclin Dependent Kinase Inhibitor 1B (CDKN1B), Cyclin Dependent Kinase Inhibitor 2C (CDKN2C), Aryl-Hydrocarbon Receptor Interacting Protein (AIP), and Protein Kinase cAMP-Dependent Type 1 Regulatory Subunit Alpha (PRKAR1A) (9–11)]. This evidence concerns the gene AIP and pituitary tumor.