title: Impact of gsp mutations in somatotroph pituitary adenomas on growth hormone response to somatostatin analogs: a meta-analysis.
abstract: OBJECTIVE
  Somatic mutations in the GNAS1 gene, which encodes the alpha-subunit of G stimulatory proteins (gsp), are frequently detected in somatotroph pituitary tumors and have been associated to specific clinical and histopathological characteristics. However, the question whether the presence of a somatic gsp mutation affects the response to somatostatin analog treatment remains unresolved.
  
  
  METHODS
  Following a literature search, we performed a meta-analysis, including 8 eligible studies, in order to estimate the effect of gsp mutation on the percent reduction of growth hormone (GH) levels during an acute octreotide suppression test (OST). A total of 310 patients with acromegaly [126 gsp (+) and 184 gsp (-)] were included in the analysis.
  
  
  RESULTS
  The presence of the gsp mutation was related with a greater reduction in GH levels on OST [Weighted Mean Difference (WMD): 9.08 % (95 % CI, 2.73, 15.42); p = 0.005; random effects model]. There was significant heterogeneity for this effect estimate (I(2) = 58 %, p value for heterogeneity = 0.02). A sensitivity analysis after exclusion of a study with different methodology of OST provided similar estimates [WMD: 6.93 % (95 % CI, 1.40, 12.46); p = 0.01], albeit with no significant heterogeneity (I(2) = 35 %, p value for heterogeneity = 0.16).
  
  
  CONCLUSIONS
  The present meta-analysis suggests a role for gsp mutation as a prognostic factor of treatment response to somatostatin analogs.
authors.affiliation: Department of Endocrinology, "Hippokration" General Hospital of Thessaloniki, Konstantinoupoleos 49, 54642, Thessaloníki, Greece. zefsta@hotmail.com.
authors.forename: Z A
authors.initials: ZA
authors.lastname: Efstathiadou
authors.affiliation: Department of Endocrinology, University of Thessaly, Larissa, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Bargiota
authors.affiliation: Department of Endocrinology-Endocrine Oncology, Theagenion Cancer Hospital, Thessaloniki, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Chrisoulidou
authors.affiliation: Endocrine Unit, Athens Naval and VA General Hospital, Athens, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Kanakis
authors.affiliation: Department of Endocrinology and Diabetes Center, Athens General Hospital "G. Gennimatas", Athens, Greece.
authors.forename: L
authors.initials: L
authors.lastname: Papanastasiou
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, University Hospital of Patras, Rio, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Theodoropoulou
authors.affiliation: Department of Endocrinology, University of Ioannina, Ioannina, Greece.
authors.forename: S K
authors.initials: SK
authors.lastname: Tigas
authors.affiliation: Endocrine Unit, Second Department of Internal Medicine, University of Athens, Medical School, "Attikon" Hospital, Athens, Greece.
authors.forename: D A
authors.initials: DA
authors.lastname: Vassiliadi
authors.affiliation: Endocrine Unit, Department of Medical Therapeutics, Athens University School of Medicine, Athens, Greece.
authors.forename: M
authors.initials: M
authors.lastname: Alevizaki
authors.affiliation: Department of Endocrinology, Evangelismos Hospital, Athens, Greece.
authors.forename: S
authors.initials: S
authors.lastname: Tsagarakis
mesh_terms: D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics*; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D009154:Mutation / Q000235:genetics; D010911:Pituitary Neoplasms / Q000235:genetics*
chemical_list: D013006:Growth Hormone; D019205:GTP-Binding Protein alpha Subunits, Gs
keywords: Acromegaly; Somatostatin analogs; gsp mutations