GNAS and multiple endocrine neoplasia type 1: Genetic studies have highlighted the role of inherited germline mutations in genes such as AIP in Familial Isolated Pituitary Adenoma [8], PRKAR1A in Carney Complex, MEN1 in multiple endocrine neoplasia syndrome type 1 (MEN 1) [9], CDKN1B in MEN 4 [10], and USP8 as an oncogene in sporadic corticotroph adenomas [11], as well as GNAS mutations in somatotroph tumors [12].