An Update on the Genetic Drivers of Corticotroph Tumorigenesis.

The genetic landscape of corticotroph tumours of the pituitary gland has dramatically changed over the last 10 years. Somatic changes in the gene account for the most common genetic defect in corticotrophinomas, especially in females, while variants in or are associated with a subset of aggressive tumours. Germline defects have also been identified in patients with Cushing's disease: some are well-established (), while others are rare and could represent coincidences.

Genetic diagnosis in acromegaly and gigantism: From research to clinical practice.

It is usually considered that only 5% of all pituitary neuroendocrine tumours are due to inheritable causes. Since this estimate was reported, however, multiple genetic defects driving syndromic and nonsyndromic somatotrophinomas have been unveiled. This heterogeneous genetic background results in overlapping phenotypes of GH excess.

Hotspots of Somatic Genetic Variation in Pituitary Neuroendocrine Tumors.

The most common genetic drivers of pituitary neuroendocrine tumors (PitNETs) lie within mutational hotspots, which are genomic regions where variants tend to cluster. Some of these hotspot defects are unique to PitNETs, while others are associated with additional neoplasms. Hotspot variants in and are the most common genetic causes of acromegaly and Cushing's disease, respectively.

Clinical Spectrum of USP8 Pathogenic Variants in Cushing's Disease.

Cushing's disease (CD) is a life-threatening condition with a challenging diagnostic process and scarce treatment options. CD is caused by usually benign adrenocorticotrophic hormone (ACTH)-secreting pituitary neuroendocrine tumors (PitNETs), known as corticotropinomas. These tumors are predominantly of sporadic origin, and usually derive from the monoclonal expansion of a mutated cell.

Germline loss-of-function variants are enriched in subjects with pituitary hypersecretion.

Introduction: Pituitary adenomas (PAs) are common, usually benign tumors of the anterior pituitary gland which, for the most part, have no known genetic cause. PAs are associated with major clinical effects due to hormonal dysregulation and tumoral impingement on vital brain structures. PAM encodes a multifunctional protein responsible for the essential C-terminal amidation of secreted peptides.

Determinants of Clinical Behavior and Prognosis in Cushing's Disease: A Quest for Useful Biomarkers.

Cushing's disease (CD) is the most common cause of endogenous hypercortisolemia. The clinical management of this condition is complex and entails multiple therapeutic strategies, treatment of chronic comorbidities, and lifelong surveillance for recurrences and complications. The identification of robust, practical, and reliable markers of disease behavior and prognosis could potentially allow for a tailored and cost-efficient management of each patient, as well as for a reduction of the medical procedure-associated stress.

Genetic drivers of Cushing's disease: Frequency and associated phenotypes.

Purpose: Cushing's disease (CD) is often explained by a single somatic sequence change. Germline defects, however, often go unrecognized. We aimed to determine the frequency and associated phenotypes of genetic drivers of CD in a large cohort.

Whole Exome Sequencing in Patients With Ectopic Posterior Pituitary.

Context: Ectopic posterior pituitary (EPP), a condition in which the posterior pituitary gland is displaced due to defective neuronal migration, is frequently associated with hypopituitarism. Genetic variants play a role, but many cases remain unexplained.

Objective: A large EPP cohort was studied to explore the importance of genetic variants and how they correlate with clinical findings.

Clinical and genetic characteristics in patients under 30 years with sporadic pituitary adenomas.

Objective: Pituitary adenomas (PA) are rare in young patients, and additional studies are needed to fully understand their pathogenesis in this population. We describe the clinical and genetic characteristics of apparently sporadic PA in a cohort of young patients.

Design: Clinical and molecular analysis of 235 patients (age ≤ 30 years) with PA.

The X-linked acrogigantism-associated gene gpr101 is a regulator of early embryonic development and growth in zebrafish.

We recently described X-linked acrogigantism (X-LAG), a condition of early childhood-onset pituitary gigantism associated with microduplications of the GPR101 receptor. The expression of GPR101 in hyperplastic pituitary regions and tumors in X-LAG patients, and GPR101's normally transient pituitary expression during fetal development, suggest a role in the regulation of growth. Nevertheless, little is still known about GPR101's physiological functions, especially during development.

Potential markers of disease behavior in acromegaly and gigantism.

: Acromegaly and gigantism entail increased morbidity and mortality if left untreated, due to the systemic effects of chronic GH and IGF-1 excess. Guidelines for the diagnosis and treatment of patients with GH excess are well established; however, the presentation, clinical behavior and response to treatment greatly vary among patients. Numerous markers of disease behavior are routinely used in medical practice, but additional biomarkers have been recently identified as a result of basic and clinical research studies.

Germline CDKN1B Loss-of-Function Variants Cause Pediatric Cushing's Disease With or Without an MEN4 Phenotype.

Context: Germline loss-of-function CDKN1B gene variants cause the autosomal dominant syndrome of multiple endocrine neoplasia type 4 (MEN4). Even though pituitary neuroendocrine tumors are a well-known component of the syndrome, only 2 cases of Cushing's disease (CD) have so far been described in this setting.

Aim: To screen a large cohort of CD patients for CDKN1B gene defects and to determine their functional effects.

Significant Benefits of AIP Testing and Clinical Screening in Familial Isolated and Young-onset Pituitary Tumors.

Context: Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are responsible for a subset of familial isolated pituitary adenoma (FIPA) cases and sporadic pituitary neuroendocrine tumors (PitNETs).

Objective: To compare prospectively diagnosed AIP mutation-positive (AIPmut) PitNET patients with clinically presenting patients and to compare the clinical characteristics of AIPmut and AIPneg PitNET patients.

Design: 12-year prospective, observational study.

Germline USP8 Mutation Associated With Pediatric Cushing Disease and Other Clinical Features: A New Syndrome.

Background: Somatic mutations in the ubiquitin-specific peptidase 8 (USP8) gene are common in corticotropinomas of children with Cushing disease (CD). We report a unique patient with a germline USP8 mutation who presented with CD and a constellation of other findings that constitute an intriguing genetic syndrome.

Case Description: We describe a 16-year-old female with CD, developmental delay, dysmorphic features, ichthyosiform hyperkeratosis, chronic lung disease, chronic kidney disease, hyperglycemia, dilated cardiomyopathy with congestive heart failure, and previous history of hyperinsulinism and partial GH deficiency.

Large Genomic Aberrations in Corticotropinomas Are Associated With Greater Aggressiveness.

Context: Genomic losses/gains are associated with cancer progression and prognosis. In pituitary adenomas, analyses of copy number variations (CNVs) have shown that a subset of adenomas have higher genomic variability. However, whether CNVs are associated with tumor aggressiveness and prognosis has not been determined.

Children with MEN1 gene mutations may present first (and at a young age) with Cushing disease.

Objective: Cushing disease (CD) is a rare entity caused by ACTH-secreting pituitary tumours, leading to prolonged hypercortisolism. Most cases are sporadic but can rarely occur in the context of familial predisposition, due to germline mutations in genes such as MEN1, leading to multiple endocrine neoplasia type 1, MEN1. We have reported previously that CD can be the first and only presenting manifestation of MEN1.

Genetics of Cushing's Syndrome.

The knowledge on the molecular and genetic causes of Cushing's syndrome (CS) has greatly increased in the recent years. Somatic mutations leading to overactive 3',5'-cyclic adenosine monophosphate/protein kinase A and wingless-type MMTV integration site family/beta-catenin pathways are the main molecular mechanisms underlying adrenocortical tumorigenesis. Corticotropinomas are characterized by resistance to glucocorticoid negative feedback, impaired cell cycle control and overexpression of pathways sustaining ACTH secretion.

An orphan G-protein-coupled receptor causes human gigantism and/or acromegaly: Molecular biology and clinical correlations.

X-linked acrogigantism (X-LAG) is a recently described form of familial or sporadic pituitary gigantism characterized by very early onset GH and IGF-1 excess, accelerated growth velocity, gigantism and/or acromegaloid features. Germline or somatic microduplications of the Xq26.3 chromosomal region, invariably involving the GPR101 gene, constitute the genetic defect leading to X-LAG.

Multi-chaperone function modulation and association with cytoskeletal proteins are key features of the function of AIP in the pituitary gland.

Despite the well-recognized role of loss-of-function mutations of the aryl hydrocarbon receptor interacting protein gene () predisposing to pituitary adenomas, the pituitary-specific function of this tumor suppressor remains an enigma. To determine the repertoire of interacting partners for the AIP protein in somatotroph cells, wild-type and variant AIP proteins were used for pull-down/quantitative mass spectrometry experiments against lysates of rat somatotropinoma-derived cells; relevant findings were validated by co-immunoprecipitation and co-localization. Global gene expression was studied in mutation positive and negative pituitary adenomas via RNA microarrays.

Risk category system to identify pituitary adenoma patients with mutations.

Background: Predictive tools to identify patients at risk for gene mutations related to pituitary adenomas are very helpful in clinical practice. We therefore aimed to develop and validate a reliable risk category system for aryl hydrocarbon receptor-interacting protein () mutations in patients with pituitary adenomas.

Methods: An international cohort of 2227 subjects were consecutively recruited between 2007 and 2016, including patients with pituitary adenomas (familial and sporadic) and their relatives.

Corticotropinoma as a Component of Carney Complex.

Known germline gene abnormalities cause one-fifth of the pituitary adenomas in children and adolescents, but, in contrast with other pituitary tumor types, the genetic causes of corticotropinomas are largely unknown. In this study, we report a case of Cushing disease (CD) due to a loss-of-function mutation in , providing evidence for association of this gene with a corticotropinoma. A 15-year-old male presenting with hypercortisolemia was diagnosed with CD.

Cyclic 3',5'-adenosine monophosphate (cAMP) signaling in the anterior pituitary gland in health and disease.

The cyclic 3',5'-adenosine monophosphate (cAMP) was the first among the so-called "second messengers" to be described. It is conserved in most organisms and functions as a signal transducer by mediating the intracellular effects of multiple hormones and neurotransmitters. In this review, we first delineate how different members of the cAMP pathway ensure its correct compartmentalization and activity, mediate the terminal intracellular effects, and allow the crosstalk with other signaling pathways.

Loss-of-function mutations in the gene are a novel cause of Cushing's disease.

The cell cycle regulator participates in the adrenal-pituitary negative feedback, and its expression is reduced in corticotropinomas, pituitary tumors with a largely unexplained genetic basis. We investigated the presence of mutations/copy number variations (CNVs) and their associated clinical, histopathological and molecular features in patients with Cushing's disease (CD). Samples from 146 pediatric (118 germline DNA only/28 germline and tumor DNA) and 35 adult (tumor DNA) CD patients were screened for mutations.