The reported frequencies of Gs alpha mutations (gsp mutations) in
growth hormone (
GH)-secreting pituitary adenomas are variable (ranging from 4.4 to 43%), and the presence of these mutations in the other
pituitary adenomas is still a matter of controversy. Previous clinical and biochemical analyses of patients with
GH-secreting pituitary adenomas and gsp mutations produced conflicting results and did not demonstrate obvious characteristics. Therefore, we investigated the prevalence of gsp mutations in Korean patients with
pituitary adenomas and elucidated the characteristics of these patients. Forty-four GH-secreting
adenomas, 7
prolactin (PRL)-secreting
adenomas and 32 clinically non-functioning
adenomas were examined for the presence of point mutations in
codon 201 and 227 of the Gs alpha gene using a nested PCR and direct sequencing of
DNA extracted from fresh tissue or
paraffin-embedded
pituitary adenoma samples. Seven of the 44
GH-secreting pituitary adenomas had point mutations at
codon 201 or 227; of these, five mutations were in
codon 201 and two were in
codon 227. In patients with gsp mutations, mean
tumor size was significantly smaller than in patients without gsp mutations (15.9+/-8.7 mm vs. 24.9+/-14.9 mm, P<0.05). Age, sex, basal GH levels, GH response to oral
glucose loading, GH response to
octreotide and surgical outcome were not different in the two groups. One of the 32 clinically non-functioning
pituitary adenomas had a point mutation at
codon 201; none of the seven
prolactinomas had these mutations. These results show that gsp mutations are not rare in Korean acromegalic patients and mean
tumor size is significantly smaller in acromegalic patients with gsp mutations. Our results also confirm the low frequency of gsp mutations in clinically non-functioning
pituitary adenomas and the absence of gsp mutations in
prolactinoma.