Familial pituitary adenomas.

Department of Endocrinology, Centre Hospitalier Universitaire de Liège, University of Liège, Domaine Universitaire du Sart-Tilman, Liège 4000, Belgium.
Journal of Internal Medicine (Impact Factor: 5.79). 08/2009; 266(1):5-18. DOI: 10.1111/j.1365-2796.2009.02109.x
Source: PubMed

ABSTRACT The majority of pituitary adenomas occur sporadically, however, about 5% of all cases occur in a familial setting, of which over half are due to multiple endocrine neoplasia type 1 (MEN-1) and Carney's complex (CNC). Since the late 1990s we have described non-MEN1/CNC familial pituitary tumours that include all tumour phenotypes, a condition named familial isolated pituitary adenomas (FIPA). The clinical characteristics of FIPA vary from those of sporadic pituitary adenomas, as patients with FIPA have a younger age at diagnosis and larger tumours. About 15% of FIPA patients have mutations in the aryl hydrocarbon receptor interacting protein gene (AIP), which indicates that FIPA may have a diverse genetic pathophysiology. This review describes the clinical features of familial pituitary adenomas like MEN1, the MEN 1-like syndrome MEN-4, CNC, FIPA, the tumour pathologies found in this setting and the genetic/molecular data that have been recently reported.

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    ABSTRACT: Pituitary adenomas are neoplasms of the anterior pituitary lobe and account for 15–20% of all intracranial tumors. Although most pituitary tumors are benign they can cause severe symptoms related to tumor size as well as hypopituitarism and/or hypersecretion of one or more pituitary hormones. Most pituitary adenomas are sporadic, but it has been estimated that 5% of patients have a familial background. Germline mutations of the tumor suppressor gene aryl hydrocarbon receptor-interacting protein (AIP) predispose to hereditary pituitary neoplasia. Recently, it has been demonstrated that AIP mutations predispose to pituitary tumorigenesis through defective inhibitory GTP binding protein (Gαi) signaling. This finding prompted us to examine whether germline loss-of-function mutations in inhibitory guanine nucleotide (GTP) binding protein alpha (GNAI) loci are involved in genetic predisposition of pituitary tumors. To our knowledge, this is the first time GNAI genes are sequenced in order to examine the occurrence of inactivating germline mutations. Thus far, only somatic gain-of-function hot-spot mutations have been studied in these loci. Here, we have analyzed the coding regions of GNAI1, GNAI2, and GNAI3 in a set of young sporadic somatotropinoma patients (n = 32; mean age of diagnosis 32 years) and familial index cases (n = 14), thus in patients with a disease phenotype similar to that observed in AIP mutation carriers. In addition, expression of Gαi proteins was studied in human growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH)-secreting and non-functional pituitary tumors. No pathogenic germline mutations affecting the Gαi proteins were detected. The result suggests that loss-of-function mutations of GNAI loci are rare or nonexistent in familial pituitary adenomas.
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