Recently, mutations in aryl hydrocarbon receptor interacting protein (AIP) [1], [2] have been linked to familial isolated pituitary adenomas (FIPA) [3]–[5], a condition most often characterized by young-onset growth hormone and prolactin-secreting pituitary tumors (reviewed by [6]), which leads to acromegaly and gigantism. The gene discussed is AIP; the disease is pituitary tumor.