Abstract 1

The hypersecretion of growth hormone (GH) is usually produced by a pituitary adenoma, and causes gigantism in children and acromegaly in adults. Approximately 45% of hypersecretory adenomas show mutations in GTPase activity of G protein with the substitution of arginine (R) by histidine (H) or cysteine (C) in codon 201 of Gαs. Which is called gsp. We studied these mutations in a 12 year old boy with gigantism (accelerated growth, increased plasma GH and IGF-I associated with a pituitary macroadenoma), and in 20 pituitary tumors from adult acromegalic patients. The DNA obtained from paraffin-embedded tumoral tissue was amplified by PCR obtaining a 315 bp fragment, which was digested by the NlaIII restriction enzyme to study the R201H mutation. This mutation was found in the tumoral tissue of the child and in 8/20 of acromegalic patients. Table

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We did not observe any difference between the presence or absence of gsp and age of the patient, pre-operatory GH concentration, tumor size or requirement for radiotherapy. The R201C mutation was not found in any tumor studied by allele-specific hybridization (ASO). In conclusion, this may be the first demonstration of gsp mutation in a child with gigantism not associated with the McCune-Albright Syndrome (Ref. JCEM 81:3839, 1996). We observed the R201H mutation in the 42.9% of our patients, which constitutes a higher frequency to that reported in the literature.