GNAS and growth hormone-producing pituitary gland neoplasm: GNAS (p.Q227L, n=1; p.Q227R, n=1 and p.R201C, n=9) somatic missense mutations were found in heterozygosis in 11/41 patients with somatotropinomas (27%) and in 1/21 (p.R201C) with NFPA (4.8%) (P=0.05).