Until recently, there were only few reports regarding the genetic changes in ACTHomas, except for familial Cushing’s disease, such as multiple endocrine neoplasm type 1 (MEN1), MEN4, and familial isolated pituitary adenomas (FIPAs), and the germline mutations associated with these hereditary syndromes were identified in the MEN1, CDKN1B, and AIP genes, respectively. Here, MEN1 is linked to familial isolated pituitary adenoma.