Intriguingly, PRKAR1A mutations are not seen in sporadic somatotropinomas (i.e., those not associated with a germline mutation predisposing to adenoma formation), although somatic mutations in GNAS, as well as other genes (including USP8, BRAF,PIK3CA and TP53), are seen commonly in these tumors (46, 108–112). The gene discussed is GNAS; the disease is adenoma.