gps Mutations in Chilean patients harboring growth hormone-secreting pituitary tumors

Hypersecretion of GH is usually caused by a pituitary adenoma and about 40% of these tumors exhibit missense gsp mutations in Arg(201) or Gln(227) of the Gs(alpha) gene. We studied 20 pituitary tumors obtained from patients w ith GH hypersecretion, One tumor was resected from an 11 year-old boy with a 3 year history of accelerated growth, associated with increased concentra tions of serum GH and IGF-I, which were not suppressed by glucose administr ation, The remaining 19 tumors were obtained from adult acromegalic patient s, who had elevated baseline serum GH levels that did not show evidence of suppression after administration of glucose, The gsp mutations were studied by enzymatic digestion of the amplified PCR fragment of exon 8 (Arg(201)) and exon 9 (Gln(227)) with the enzymes NlaIII and NgoAIV, respectively. The tumors obtained from the boy and from nine of the 19 patients with acromeg aly exhibited the gsp mutation R201H. None of the tumors had the Gln(227) m utation. The gsp positive patients tended to be older, had smaller tumors, and had preoperative basal serum GH levels which were significantly lower ( 21 +/- 6 vs 56 +/- 16 mu g/l, p < 0.05) than the gsp negative patients, In this study, we documented the presence of a gsp mutation in Arg(201) in a b oy with gigantism and in approximately half of 19 Chilean adult patients wi th acromegaly, similar to other populations.