Pituitary adenomas are an incidental finding in up to 10% of unselected subjects undergoing a magnetic resonance imaging scan of the brain and in about two-thirds of cases they can be associated with the secretion of excess hormones, such as prolactin (PRL) (32–66%), growth hormone (GH) (8–16%), adrenocorticotropic hormone (ACTH) (2–6%), and, rarely, thyroid-stimulating hormone (TSH) (less than 1%) [21]. The gene discussed is GH1; the disease is pituitary gland adenoma.