GNAS and pituitary gland adenoma: In contrast, pituitary adenomas secreting GH-releasing hormone and ectopic tumors producing growth hormone are uncommon, constituting roughly 1% of cases.[3] Recent research indicates that the molecular biology of sporadic GH adenomas likely involves genes including GNAS, PTTG, PDE4D, and GPR101.[4–6] GNAS activation and PDE4D overexpression can result in cAMP buildup and excessive GH production.