According to the hormonal activity, pituitary adenomas can be defined as “functioning,” causing endocrine dysfunction such as Cushing's disease in ACTH-secreting pituitary adenomas, acromegaly in GH-secreting pituitary adenomas, galactorrhea and amenorrhea in PRL-secreting pituitary adenomas, and hyperthyroidism in TSH-secreting pituitary adenomas. The gene discussed is PRL; the disease is pituitary gland adenoma.