BACKGROUND Increased secretion of growth hormone leads to gigantism in children and acromegaly in adults; the genetic causes of gigantism and acromegaly are poorly understood. METHODS We performed clinical and genetic studies of samples obtained from 43 patients with gigantism and then sequenced an implicated gene in samples from 248 patients with acromegaly. RESULTS We observed microduplication on chromosome Xq26.3 in samples from 13 patients with gigantism; of these samples, 4 were obtained from members of two unrelated kindreds, and 9 were from patients with sporadic cases. All the patients had disease onset during early childhood. Of the patients with gigantism who did not carry an Xq26.3 microduplication, none presented before the age of 5 years. Genomic characterization of the Xq26.3 region suggests that the microduplications are generated during chromosome replication and that they contain four protein-coding genes. Only one of these genes, GPR101, which encodes a G-protein–coupled receptor, was overexpressed in patients’ pituitary lesions. We identified a recurrent GPR101 mutation (p.E308D) in 11 of 248 patients with acromegaly, with the mutation found mostly in tumors. When the mutation was transfected into rat GH3 cells, it led to increased release of growth hormone and proliferation of growth hormone–producing cells. CONCLUSIONS We describe a pediatric disorder (which we have termed X-linked acrogigantism [X-LAG]) that is caused by an Xq26.3 genomic duplication and is characterized by early-onset gigantism resulting from an excess of growth hormone. Duplication of GPR101 probably causes X-LAG. We also found a recurrent mutation in GPR101 in some adults with acromegaly. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.)
Context:Familial isolated pituitary adenoma (FIPA) due to aryl hydrocarbon receptor interacting protein (AIP) gene mutations is an autosomal dominant disease with incomplete penetrance. Clinical screening of apparently unaffected AIP mutation (AIPmut) carriers could identify previously unrecognized disease.Objective:To determine the AIP mutational status of FIPA and young pituitary adenoma patients, analyzing their clinical characteristics, and to perform clinical screening of apparently unaffected AIPmut carrier family members.Design:This was an observational, longitudinal study conducted over 7 years.Setting:International collaborative study conducted at referral centers for pituitary diseases.Participants:FIPA families (n = 216) and sporadic young-onset (≤30 y) pituitary adenoma patients (n = 404) participated in the study.Interventions:We performed genetic screening of patients for AIPmuts, clinical assessment of their family members, and genetic screening for somatic GNAS1 mutations and the germline FGFR4 p.G388R variant.Main Outcome Measure(s):We assessed clinical disease in mutation carriers, comparison of characteristics of AIPmut positive and negative patients, results of GNAS1, and FGFR4 analysis.Results:Thirty-seven FIPA families and 34 sporadic patients had AIPmuts. Patients with truncating AIPmuts had a younger age at disease onset and diagnosis, compared with patients with nontruncating AIPmuts. Somatic GNAS1 mutations were absent in tumors from AIPmut-positive patients, and the studied FGFR4 variant did not modify the disease behavior or penetrance in AIPmut-positive individuals. A total of 164 AIPmut-positive unaffected family members were identified; pituitary disease was detected in 18 of those who underwent clinical screening.Conclusions:A quarter of the AIPmut carriers screened were diagnosed with pituitary disease, justifying this screening and suggesting a variable clinical course for AIPmut-positive pituitary adenomas.
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