RESUMO
The prevalence of germline mutations in MEN1, AIP, PRKAR1A, CDKN1B and CDKN2CI is unknown among pediatric patients with pituitary adenomas (PA). In this study, we screened children with PA for mutations in these genes; somatic GNAS mutations were also studied in a limited number of growth hormone (GH) or prolactin (PRL)-secreting PA. We studied 74 and 6 patients with either isolated Cushing disease (CD) or GH- or PRL-secreting PA, respectively. We also screened four pediatric patients with CD, and four with GH/PRL-secreting tumors who had some syndromic features. There was one AIP mutation (p.Lys103Arg) among 74 CD patients. Two MEN1 mutations that occurred in patients with recurrent or difficult-to-treat disease were found among patients with CD. There was one MEN1 and three AIP mutations (p.Gln307ProfsX104, p.Pro114fsX, p.Lys241X) among pediatric patients with isolated GH- or PRL-secreting PA and one additional MEN1 mutation in a patient with positive family history. There were no mutations in the PRKAR1A, CDKN1B, CDKN2C or GNAS genes. Thus, germline AIP or MEN1 gene mutations are frequent among pediatric patients with GH- or PRL-secreting PA but are significantly rarer in pediatric CD; PRKAR1A mutations are not present in PA outside of Carney complex.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/genética , Neoplasia Endócrina Múltipla Tipo 1/genética , Hipersecreção Hipofisária de ACTH/genética , Neoplasias Hipofisárias/genética , Adolescente , Criança , Cromograninas , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/genética , Inibidor de Quinase Dependente de Ciclina p18/genética , Inibidor de Quinase Dependente de Ciclina p27 , Feminino , Subunidades alfa Gs de Proteínas de Ligação ao GTP/genética , Mutação em Linhagem Germinativa , Humanos , Masculino , Linhagem , Hipersecreção Hipofisária de ACTH/diagnóstico , Neoplasias Hipofisárias/diagnósticoRESUMO
Pediatric Cushing disease (CD) often presents with short stature, but we have observed significant inter-individual variability in the growth delay caused by endogenous hypercortisolism. Glucocorticoids cause growth retardation by affecting the growth hormone (GH) - insulin-like growth factor-1 (IGF 1) somatotropic axis, but also other, GH-independent sites. Recently, the GH receptor (GHR) gene was found to have a common polymorphism (P) that leads to a deletion (d3) or retention of exon 3. In this study, we tested the hypothesis that the GH receptor polymorphism (GHR-P) maybe one of the significant variants that determines the degree of growth delay among patients with CD. GHR genotyping was performed on 56 children with newly diagnosed CD (24 females, 32 males, mean age of 12.9+/-3.3 years) who were followed at our institution between the years 1997-2007. Correlation analysis included genotype, measures of growth and the somatotropic axis, and anthropometrics. Within the group, 31 (12 girls, 19 boys) expressed the full length GHR allele, 10 (4 girls, 6 boys) were d3-GHR homozygotes and 15 (7 girls, 8 boys) were d3-GHR heterozygotes. No significant differences were found between the GHR genotypes and patient's height and/or growth velocity, or any other measures that we evaluated. The presence of a well-studied and common GHR polymorphism does not appear to be responsible for the variability of growth delay observed in patients with Cushing disease.
Assuntos
Transtornos do Crescimento/complicações , Transtornos do Crescimento/genética , Fator de Crescimento Insulin-Like I/metabolismo , Hipersecreção Hipofisária de ACTH/complicações , Hipersecreção Hipofisária de ACTH/genética , Polimorfismo de Nucleotídeo Único/genética , Receptores da Somatotropina/genética , Adolescente , Estatura , Índice de Massa Corporal , Criança , Feminino , Estudos de Associação Genética , Humanos , MasculinoRESUMO
Prolactinomas are rare tumors in prepubertal children. A prolactinoma in a young child may be due to sequence variants in genes that are known to cause these tumors ( MEN1, PRKAR1A, AIP). An 11-year-old boy with a macroprolactinoma was treated with cabergoline and the tumor receded. We studied the patient and his family for genetic causes of this tumor. No mutations were present in the coding sequence of PRKAR1A and AIP. A novel heterozygous substitution (IVS3-7 c>a) was identified in intron 3 of MEN1. We also found an additional PCR amplicon that incorporated the entire intron 3 of the gene (210 bp) in the patient's cDNA. The same amplicon was present with lower intensity in some of the control individuals who were not mutation carriers. Intron 3 harbors an in-frame stop codon and its incorporation is predicted to result in a prematurely terminated protein. We conclude that a novel MEN1 variation was identified in a young boy with prolactinoma and six of his relatives who did not present with prolactinoma or other MEN1 related symptoms. This novel MEN1 variation may be associated with low penetrance of the disease. The IVS3-7 c>a defect is suggested to be pathogenic because it is associated with lower menin levels in the cells of these patients, but its consequences may be mitigated by a variety of factors including changes in transcription and translation of the MEN1 gene.
