The Genetic Pathophysiology and Clinical Management of the TADopathy, X-Linked Acrogigantism.

Pituitary gigantism is a rare manifestation of chronic growth hormone (GH) excess that begins before closure of the growth plates. Nearly half of pituitary gigantism patients have an identifiable genetic cause. X-linked acrogigantism (X-LAG; 10% of pituitary gigantism) typically begins during infancy and can lead to the tallest individuals described. In the 10 years since its discovery, about 40 patients have been identified. Patients with X-LAG usually develop mixed GH and prolactin macroadenomas with occasional hyperplasia that secrete copious amounts of GH, and frequently prolactin. Circulating GH releasing hormone (GHRH) is also elevated in a proportion of patients. X-LAG is caused by constitutive or sporadic mosaic duplications at chromosome Xq26.3 that disrupt the normal chromatin architecture of a topologically associating domain (TAD) around the orphan G protein coupled receptor (GPCR), GPR101. This leads to the formation of a neoTAD in which GPR101 over-expression is driven by ectopic enhancers ("TADopathy"). X-LAG has been seen in three families due to transmission of the duplication from affected mothers to sons. GPR101 is a constitutively active receptor with an unknown natural ligand that signals via multiple G proteins and protein kinases A and C to promote GH/prolactin hypersecretion. Treatment of X-LAG is challenging due to the young patient population and resistance to somatostatin analogs; the GH receptor antagonist pegvisomant is often an effective option. GH, insulin-like growth factor 1 (IGF-1) and prolactin hypersecretion and physical overgrowth can be controlled before definitive adult gigantism occurs, often at the cost of permanent hypopituitarism.

Case report: Management of pediatric gigantism caused by the TADopathy, X-linked acrogigantism.

X-linked acrogigantism (X-LAG) is a rare form of pituitary gigantism that is associated with growth hormone (GH) and prolactin-secreting pituitary adenomas/pituitary neuroendocrine tumors (PitNETs) that develop in infancy. It is caused by a duplication on chromosome Xq26.3 that leads to the misexpression of the gene GPR101, a constitutively active stimulator of pituitary GH and prolactin secretion. GPR101 normally exists within its own topologically associating domain (TAD) and is insulated from surrounding regulatory elements. X-LAG is a TADopathy in which the duplication disrupts a conserved TAD border, leading to a neo-TAD in which ectopic enhancers drive GPR101 over-expression, thus causing gigantism. Here we trace the full diagnostic and therapeutic pathway of a female patient with X-LAG from 4C-seq studies demonstrating the neo-TAD through medical and surgical interventions and detailed tumor histopathology. The complex nature of treating young children with X-LAG is illustrated, including the achievement of hormonal control using a combination of neurosurgery and adult doses of first-generation somatostatin analogs.

The clinical and therapeutic profiles of prolactinomas associated with germline pathogenic variants in the aryl hydrocarbon receptor interacting protein (AIP) gene.

Introduction: Prolactinomas are the most frequent type of pituitary adenoma encountered in clinical practice. Dopamine agonists (DA) like cabergoline typically provide sign/ symptom control, normalize prolactin levels and decrease tumor size in most patients. DA-resistant prolactinomas are infrequent and can occur in association with some genetic causes like MEN1 and pathogenic germline variants in the AIP gene (AIPvar). Methods: We compared the clinical, radiological, and therapeutic characteristics of AIPvar-related prolactinomas (n=13) with unselected hospital-treated prolactinomas ("unselected", n=41) and genetically-negative, DA-resistant prolactinomas (DA-resistant, n=39). Results: AIPvar-related prolactinomas occurred at a significantly younger age than the unselected or DA-resistant prolactinomas (p<0.01). Males were more common in the AIPvar (75.0%) and DA- resistant (49.7%) versus unselected prolactinomas (9.8%; p<0.001). AIPvar prolactinomas exhibited significantly more frequent invasion than the other groups (p<0.001) and exhibited a trend to larger tumor diameter. The DA-resistant group had significantly higher prolactin levels at diagnosis than the AIPvar group (p<0.001). Maximum DA doses were significantly higher in the AIPvar and DA-resistant groups versus unselected. DA-induced macroadenoma shrinkage (>50%) occurred in 58.3% in the AIPvar group versus 4.2% in the DA-resistant group (p<0.01). Surgery was more frequent in the AIPvar and DA- resistant groups (43.8% and 61.5%, respectively) versus unselected (19.5%: p<0.01). Radiotherapy was used only in AIPvar (18.8%) and DA-resistant (25.6%) groups. Discussion: AIPvar confer an aggressive phenotype in prolactinomas, with invasive tumors occurring at a younger age. These characteristics can help differentiate rare AIPvar related prolactinomas from DA-resistant, genetically-negative tumors.

Germline loss-of-function PAM 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. Methods: Following the identification of a loss-of-function variant (p.Arg703Gln) in the peptidylglycine a-amidating monooxygenase (PAM) gene in a family with pituitary gigantism, we investigated 299 individuals with sporadic PAs and 17 familial isolated PA kindreds for PAM variants. Genetic screening was performed by germline and tumor sequencing and germline copy number variation (CNV) analysis. Results: In germline DNA, we detected seven heterozygous, likely pathogenic missense, truncating, and regulatory SNVs. These SNVs were found in sporadic subjects with growth hormone excess (p.Gly552Arg and p.Phe759Ser), pediatric Cushing disease (c.-133T>C and p.His778fs), or different types of PAs (c.-361G>A, p.Ser539Trp, and p.Asp563Gly). The SNVs were functionally tested in vitro for protein expression and trafficking by Western blotting, splicing by minigene assays, and amidation activity in cell lysates and serum samples. These analyses confirmed a deleterious effect on protein expression and/or function. By interrogating 200,000 exomes from the UK Biobank, we confirmed a significant association of the PAM gene and rare PAM SNVs with diagnoses linked to pituitary gland hyperfunction. Conclusion: The identification of PAM as a candidate gene associated with pituitary hypersecretion opens the possibility of developing novel therapeutics based on altering PAM function.

The Role of MCM9 in the Etiology of Sertoli Cell-Only Syndrome and Premature Ovarian Insufficiency.

Infertility in couples is a common problem, with both female and male factors contributing to similar extents. Severe, congenital disorders affecting fertility are, however, rare. While folliculogenesis and spermatogenesis are generally orchestrated via different mechanisms, some genetic anomalies can impair both female and male gametogenesis. Minichromosome maintenance complex component 9 (MCM9) is involved in DNA repair and mutations of the MCM9 gene have been previously reported in females with premature ovarian insufficiency (POI). MCM9 is also an emerging cancer risk gene. We performed next-generation and Sanger sequencing of fertility and related genes and hormonal and imaging studies in a kindred whose members had POI and disordered spermatogenesis. We identified a homozygous pathogenic MCM9 variant, c.394C>T (p.Arg132*) in three sisters affected by POI due to ovarian dysgenesis and their brother who had normal pubertal development but suffered from non-obstructive azoospermia. Testicular biopsy revealed Sertoli cell-only testicular histopathology. No evidence of early onset cancer was found in the homozygotic family members, but they were all young (<30 years) at the time of the study. In the male patient the homozygous MCM9 variant led to normal pubertal development and hormonal levels but caused a Sertoli-cell-only syndrome with non-obstructive azoospermia. In the homozygous females studied, the clinical, hormonal, and gonadal phenotypes revealed ovarian dysgenesis consistent with previous reports. Active screening for potential colorectal and other cancer risks in the homozygotic MCM9 subjects has been instigated.

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

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. Following the identification of a loss-of-function variant (p.Arg703Gln) in the PAM gene in a family with pituitary gigantism, we investigated 299 individuals with sporadic PAs and 17 familial isolated pituitary adenomas kindreds for PAM variants. PAM encodes a multifunctional protein responsible for the essential C-terminal amidation of secreted peptides. Genetic screening was performed by germline and tumor sequencing and germline copy number variation (CNV) analysis. No germline CNVs or somatic single nucleotide variants (SNVs) were identified. We detected seven likely pathogenic heterozygous missense, truncating, and regulatory SNVs. These SNVs were found in sporadic subjects with GH excess (p.Gly552Arg and p.Phe759Ser), pediatric Cushing disease (c.-133T>C and p.His778fs), or with different types of PAs (c.-361G>A, p.Ser539Trp, and p.Asp563Gly). The SNVs were functionally tested in vitro for protein expression and trafficking by Western blotting, for splicing by minigene assays, and for amidation activity in cell lysates and serum samples. These analyses confirmed a deleterious effect on protein expression and/or function. By interrogating 200,000 exomes from the UK Biobank, we confirmed a significant association of the PAM gene and rare PAM SNVs to diagnoses linked to pituitary gland hyperfunction. Identification of PAM as a candidate gene associated with pituitary hypersecretion opens the possibility of developing novel therapeutics based on altering PAM function.

Complicated Clinical Course in Incipient Gigantism Due to Treatment-resistant Aryl Hydrocarbon Receptor-Interacting Protein-mutated Pediatric Somatotropinoma.

Background: Our objective was to describe the clinical course and treatment challenges in a very young patient with a pituitary adenoma due to a novel aryl hydrocarbon receptor-interacting protein (AIP) gene mutation, highlighting the limitations of somatostatin receptor immunohistochemistry to predict clinical responses to somatostatin analogs in acromegaly. Case Report: We report the case of a 7-year-old boy presenting with headache, visual field defects, and accelerated growth following failure to thrive. The laboratory results showed high insulin-like growth factor I (IGF-I) (standardised deviation scores ( +3.49) and prolactin levels (0.5 nmol/L), and magnetic resonance imaging identified a pituitary macroadenoma. Tumoral/hormonal control could not be achieved despite 3 neurosurgical procedures, each time with apparent total resection or with lanreotide or pasireotide. IGF-I levels decreased with the GH receptor antagonist pegvisomant. The loss of somatostatin receptor 5 was observed between the second and third tumor resection. In vitro, no effect on tumoral GH release by pasireotide (with/without cabergoline) was observed. Genetic analysis revealed a novel germline AIP mutation: p.Tyr202∗ (pathogenic; class 4). Discussion: In vitro response of tumor tissue to somatostatin may better predict tumoral in vivo responses of somatostatin analogs than somatostatin receptor immunohistochemistry. Conclusion: We identified a novel pathologic AIP mutation that was associated with incipient acrogigantism in an extremely young patient who had a complicated course of disease. Growth acceleration can be masked due to failure to thrive. Tumoral growth hormone release in vivo may be predicted with in vitro exposure to somatostatin receptor analogs, as it cannot be assumed that all AIP-mutated somatotropinomas respond well to pasireotide.

Pituitary MRI Features in Acromegaly Resulting From Ectopic GHRH Secretion From a Neuroendocrine Tumor: Analysis of 30 Cases.

CONTEXT: Ectopic acromegaly is a consequence of rare neuroendocrine tumors (NETs) that secrete GHRH. This abnormal GHRH secretion drives GH and IGF-1 excess, with a clinical presentation similar to classical pituitary acromegaly. Identifying the underlying cause for the GH hypersecretion in the setting of ectopic GHRH excess is, however, essential for proper management both of acromegaly and the NET. Owing to the rarity of NETs, the imaging characteristics of the pituitary in ectopic acromegaly have not been analyzed in depth in a large series. OBJECTIVE: Characterize pituitary magnetic resonance imaging (MRI) features at baseline and after NET treatment in patients with ectopic acromegaly. DESIGN: Multicenter, international, retrospective. SETTING: Tertiary referral pituitary centers. PATIENTS: Thirty ectopic acromegaly patients having GHRH hypersecretion. INTERVENTION: None. MAIN OUTCOME MEASURE: MRI characteristics of pituitary gland, particularly T2-weighted signal. RESULTS: In 30 patients with ectopic GHRH-induced acromegaly, we found that most patients had hyperplastic pituitaries. Hyperplasia was usually moderate but was occasionally subtle, with only small volume increases compared with normal ranges for age and sex. T2-weighted signal was hypointense in most patients, especially in those with hyperplastic pituitaries. After treatment of the NET, pituitary size diminished and T2-weighted signal tended to normalize. CONCLUSIONS: This comprehensive study of pituitary MRI characteristics in ectopic acromegaly underlines the utility of performing T2-weighted sequences in the MRI evaluation of patients with acromegaly as an additional tool that can help to establish the correct diagnosis.

Duplications disrupt chromatin architecture and rewire GPR101-enhancer communication in X-linked acrogigantism.

X-linked acrogigantism (X-LAG) is the most severe form of pituitary gigantism and is characterized by aggressive growth hormone (GH)-secreting pituitary tumors that occur in early childhood. X-LAG is associated with chromosome Xq26.3 duplications (the X-LAG locus typically includes VGLL1, CD40LG, ARHGEF6, RBMX, and GPR101) that lead to massive pituitary tumoral expression of GPR101, a novel regulator of GH secretion. The mechanism by which the duplications lead to marked pituitary misexpression of GPR101 alone was previously unclear. Using Hi-C and 4C-seq, we characterized the normal chromatin structure at the X-LAG locus. We showed that GPR101 is located within a topologically associating domain (TAD) delineated by a tissue-invariant border that separates it from centromeric genes and regulatory sequences. Next, using 4C-seq with GPR101, RBMX, and VGLL1 viewpoints, we showed that the duplications in multiple X-LAG-affected individuals led to ectopic interactions that crossed the invariant TAD border, indicating the existence of a similar and consistent mechanism of neo-TAD formation in X-LAG. We then identified several pituitary active cis-regulatory elements (CREs) within the neo-TAD and demonstrated in vitro that one of them significantly enhanced reporter gene expression. At the same time, we showed that the GPR101 promoter permits the incorporation of new regulatory information. Our results indicate that X-LAG is a TADopathy of the endocrine system in which Xq26.3 duplications disrupt the local chromatin architecture forming a neo-TAD. Rewiring GPR101-enhancer interaction within the new regulatory unit is likely to cause the high levels of aberrant expression of GPR101 in pituitary tumors caused by X-LAG.

Dutch founder SDHB exon 3 deletion in patients with pheochromocytoma-paraganglioma in South Africa.

Objective: Screening studies have established genetic risk profiles for diseases such as multiple endocrine neoplasia type 1 (MEN1) and pheochromocytoma-paraganglioma (PPGL). Founder effects play an important role in the regional/national epidemiology of endocrine cancers, particularly PPGL. Founder effects in the Netherlands have been described for various diseases, some of which established themselves in South Africa due to Dutch emigration. The role of Dutch founder effects in South Africa has not been explored in PPGL. Design: We performed a single-center study in South Africa of the germline genetic causes of isolated/syndromic neuroendocrine tumors. Methods: Next-generation panel, Sanger sequencing and multiplex ligand-dependent probe amplification for endocrine neoplasia risk genes. Results: From a group of 13 patients, we identified 6 with PPGL, 4 with sporadic or familial isolated pituitary adenomas, and 3 with clinical MEN1; genetic variants were identified in 9/13 cases. We identified the Dutch founder exon 3 deletion in SDHB in two apparently unrelated individuals with distinct ethnic backgrounds that had metastatic PPGL. Asymptomatic carriers with this Dutch founder SDHBexon 3 deletion were also identified. Other PPGL patients had variants in SDHB, and SDHD and three MEN1variants were identified among MEN1 and young-onset pituitary adenoma patients. Conclusions: This is the first identification of a Dutch founder effect for PPGL in South Africa. Awareness of the presence of this exon 3 SDHB deletion could promote targeted screening at a local level. Insights into PPGL genetics in South Africa could be achieved by studying existing patient databases for Dutch founder mutations in SDHx genes.

GPR101 drives growth hormone hypersecretion and gigantism in mice via constitutive activation of Gs and Gq/11.

Growth hormone (GH) is a key modulator of growth and GH over-secretion can lead to gigantism. One form is X-linked acrogigantism (X-LAG), in which infants develop GH-secreting pituitary tumors over-expressing the orphan G-protein coupled receptor, GPR101. The role of GPR101 in GH secretion remains obscure. We studied GPR101 signaling pathways and their effects in HEK293 and rat pituitary GH3 cell lines, human tumors and in transgenic mice with elevated somatotrope Gpr101 expression driven by the rat Ghrhr promoter (GhrhrGpr101). Here, we report that Gpr101 causes elevated GH/prolactin secretion in transgenic GhrhrGpr101 mice but without hyperplasia/tumorigenesis. We show that GPR101 constitutively activates not only Gs, but also Gq/11 and G12/13, which leads to GH secretion but not proliferation. These signatures of GPR101 signaling, notably PKC activation, are also present in human pituitary tumors with high GPR101 expression. These results underline a role for GPR101 in the regulation of somatotrope axis function.

miR-34a is upregulated in AIP-mutated somatotropinomas and promotes octreotide resistance.

Pituitary adenomas (PAs) are intracranial tumors associated with significant morbidity due to hormonal dysregulation, mass effects and have a heavy treatment burden. Growth hormone (GH)-secreting PAs (somatotropinomas) cause acromegaly-gigantism. Genetic forms of somatotropinomas due to germline AIP mutations (AIPmut+) have an early onset and are aggressive and resistant to treatment with somatostatin analogs (SSAs), including octreotide. The molecular underpinnings of these clinical features remain unclear. We investigated the role of miRNA dysregulation in AIPmut+ vs AIPmut- PA samples by array analysis. miR-34a and miR-145 were highly expressed in AIPmut+ vs AIPmut- somatotropinomas. Ectopic expression of AIPmut (p.R271W) in Aip-/- mouse embryonic fibroblasts (MEFs) upregulated miR-34a and miR-145, establishing a causal link between AIPmut and miRNA expression. In PA cells (GH3), miR-34a overexpression promoted proliferation, clonogenicity, migration and suppressed apoptosis, whereas miR-145 moderately affected proliferation and apoptosis. Moreover, high miR-34a expression increased intracellular cAMP, a critical mitogenic factor in PAs. Crucially, high miR-34a expression significantly blunted octreotide-mediated GH inhibition and antiproliferative effects. miR-34a directly targets Gnai2 encoding Gαi2, a G protein subunit inhibiting cAMP production. Accordingly, Gαi2 levels were significantly lower in AIPmut+ vs AIPmut- PA. Taken together, somatotropinomas with AIP mutations overexpress miR-34a, which in turn downregulates Gαi2 expression, increases cAMP concentration and ultimately promotes cell growth. Upregulation of miR-34a also impairs the hormonal and antiproliferative response of PA cells to octreotide. Thus, miR-34a is a novel downstream target of mutant AIP that promotes a cellular phenotype mirroring the aggressive clinical features of AIPmut+ acromegaly.

The Epidemiology of Pituitary Adenomas.

Pituitary adenomas are usually nonmalignant, but have a heavy burden on patients and health care systems. Increased availability of MRI has led to an increase in incidentally found pituitary lesions and clinically relevant pituitary adenomas. Epidemiologic studies show that pituitary adenomas are increasing in incidence (between 3.9 and 7.4 cases per 100,000 per year) and prevalence (76 to 116 cases per 100,000 population) in the general population (approximately 1 case per 1000 of the general population). Most new cases diagnosed are prolactinomas and nonsecreting pituitary adenomas. Most clinically relevant pituitary adenomas occur in females, but pituitary adenomas are clinically heterogeneous.

Differentiated thyroid carcinoma in sporadic and familial presentations of acromegaly: A case series.

BACKGROUND: In acromegaly, chronic growth hormone (GH) and insulin-like growth factor-1 (IGF-1) exacerbate comorbidities in multiple organs. Differentiated thyroid carcinoma (DTC) has been reported as being a comorbid condition in acromegaly. Acromegaly is usuallysporadic, but 5% of cases may be genetic. The most frequent inheritable form of acromegaly is related to germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene. Epidemiological data on the relationship between active acromegaly, its familial forms and DTC are sparse. We present the investigation of a FIPA family (familial isolated pituitary adenoma) with homogeneous acromegaly and 6 sporadic acromegaly patients with DTC. PATIENTS AND METHODS: A study of 59 acromegaly patients assessed thyroid nodules on ultrasound and fine-needle aspiration biopsy following the ATA 2015 criteria. We diagnosed 7 differentiated thyroid carcinomas. Resected thyroid carcinoma tissues were stained using an anti-AIP antibody. Analysis of germline and tumor-derived DNA for variants in the AIP and MEN1 genes were performed in the FIPA kindred. RESULTS: We describe one FIPA patient and 6 sporadic acromegaly cases with DTC. The FIPA family (AIP mutation negative) consisted of two sisters, one of whom had a DTC with intermediate risk and incomplete structural response to therapy. In our study, DTC in sporadic acromegaly had a low recurrence rate (6/6), and excellent response to therapy (6/6). Immunohistochemistry for AIP showed similar or increased staining intensity in DTC versus normal thyroid tissue. CONCLUSION: In our cohort of sporadic and familial forms of acromegaly with DTC, AIP did not appear to influence thyroid cancer progression.

Pituitary Disease in AIP Mutation-Positive Familial Isolated Pituitary Adenoma (FIPA): A Kindred-Based Overview.

Clinically-relevant pituitary adenomas occur in about 1:1000 of the general population, but only about 5% occur in a known genetic or familial setting. Familial isolated pituitary adenomas (FIPA) are one of the most important inherited settings for pituitary adenomas and the most frequent genetic cause is a germline mutation in the aryl hydrocarbon receptor-interacting protein (AIP) gene. AIP mutations lead to young-onset macroadenomas that are difficult to treat. Most are growth hormone secreting tumors, but all other secretory types can exist and the clinical profile of affected patients is variable. We present an overview of the current understanding of AIP mutation-related pituitary disease and illustrate various key clinical factors using examples from one of the largest AIP mutation-positive FIPA families identified to date, in which six mutation-affected members with pituitary disease have been diagnosed. We highlight various clinically significant features of FIPA and AIP mutations, including issues related to patients with acromegaly, prolactinoma, apoplexy and non-functioning pituitary adenomas. The challenges faced by these AIP mutation-positive patients due to their disease and the long-term outcomes in older patients are discussed. Similarly, the pitfalls encountered due to incomplete penetrance of pituitary adenomas in AIP-mutated kindreds are discussed.

Pancreatic Neuroendocrine Neoplasm Associated with a Familial MAX Deletion.

Most pancreatic neuroendocrine neoplasms (pNEN) occur sporadically but they can also occur as part of multiple endocrine neoplasia type 1 (MEN1). MAX was originally described as an inherited pheochromocytoma-paraganglioma risk gene, but also has recently been implicated in pituitary tumorigenesis. Here we describe the first case of a pNEN associated with an inherited MAX gene deletion in a family with endocrine tumors. The patient was a male carrier of an intragenic exon 3 deletion inherited from his father who had recurrent pheochromocytomas and a macroprolactinoma. The patient underwent screening and hormonal studies but no pheochromocytoma-paraganglioma, pituitary or renal tumors were identified. However, abdominal magnetic resonance imaging (MRI) identified a 1 cm lesion in body of the pancreas. The lesion was hyperintense on T2-weighted signal, and there was hyperfixation of the tumor on 68Ga-DOTANOC PET-CT images. No biochemical evidence of pancreatic hormone excess was identified. Following a guided biopsy, a pathological diagnosis of a low grade pNEN was made and immunohistochemistry showed loss of MAX nuclear staining. Genetic analysis of the tumor tissue indicated copy number neutral loss of heterozygosity consistent with uniparental disomy. This is the first reported case of a MAX deletion associated pNEN and strengthens the argument that MAX may represent an inheritable multiple endocrine neoplasia risk gene. Further analysis of germline and somatic MAX mutations/deletions in large cohorts of unexplained NEN cases could help clarify the potential role of MAX in NEN etiology.

Multivariable Prediction Model for Biochemical Response to First-Generation Somatostatin Receptor Ligands in Acromegaly.

CONTEXT: First-generation somatostatin receptor ligands (fg-SRLs) represent the mainstay of medical therapy for acromegaly, but they provide biochemical control of disease in only a subset of patients. Various pretreatment biomarkers might affect biochemical response to fg-SRLs. OBJECTIVE: To identify clinical predictors of the biochemical response to fg-SRLs monotherapy defined as biochemical response (insulin-like growth factor (IGF)-1 ≤ 1.3 × ULN (upper limit of normal)), partial response (>20% relative IGF-1 reduction without normalization), and nonresponse (≤20% relative IGF-1 reduction), and IGF-1 reduction. DESIGN: Retrospective multicenter study. SETTING: Eight participating European centers. METHODS: We performed a meta-analysis of participant data from 2 cohorts (Rotterdam and Liège acromegaly survey, 622 out of 3520 patients). Multivariable regression models were used to identify predictors of biochemical response to fg-SRL monotherapy. RESULTS: Lower IGF-1 concentration at baseline (odds ratio (OR) = 0.82, 95% confidence interval (CI) 0.72-0.95 IGF-1 ULN, P = .0073) and lower bodyweight (OR = 0.99, 95% CI 0.98-0.99 kg, P = .038) were associated with biochemical response. Higher IGF-1 concentration at baseline (OR = 1.40, (1.19-1.65) IGF-1 ULN, P ≤ .0001), the presence of type 2 diabetes (oral medication OR = 2.48, (1.43-4.29), P = .0013; insulin therapy OR = 2.65, (1.02-6.70), P = .045), and higher bodyweight (OR = 1.02, (1.01-1.04) kg, P = .0023) were associated with achieving partial response. Younger patients at diagnosis are more likely to achieve nonresponse (OR = 0.96, (0.94-0.99) year, P = .0070). Baseline IGF-1 and growth hormone concentration at diagnosis were associated with absolute IGF-1 reduction (ß = 0.90, standard error (SE) = 0.02, P ≤ .0001 and ß â€…= 0.002, SE = 0.001, P = .014, respectively). CONCLUSION: Baseline IGF-1 concentration was the best predictor of biochemical response to fg-SRL, followed by bodyweight, while younger patients were more likely to achieve nonresponse.

Clinical and Molecular Update on Genetic Causes of Pituitary Adenomas.

Pituitary adenomas are benign tumors with variable functional characteristics that can have a significant impact on patients. The majority arise sporadically, but an inherited genetic susceptibility is increasingly being recognized. Recent advances in genetics have widened the scope of our understanding of pituitary tumorigenesis. The clinical and genetic characteristics of pituitary adenomas that develop in the setting of germline-mosaic and somatic GNAS mutations (McCune-Albright syndrome and sporadic acromegaly), germline MEN1 mutations (multiple endocrine neoplasia type 1), and germline PRKAR1A mutations (Carney complex) have been well described. Non-syndromic familial cases of isolated pituitary tumors can occur as familial isolated pituitary adenomas (FIPA); mutations/deletions of the AIP gene have been found in a minority of these. Genetic alterations in GPR101 have been identified recently as causing X-linked acro-gigantism (X-LAG) leading to very early-onset pediatric gigantism. Associations of pituitary adenomas with other tumors have been described in syndromes like multiple endocrine neoplasia type 4, pheochromocytoma-paraganglioma with pituitary adenoma association (3PAs) syndrome and some of their genetic causes have been elucidated. The genetic etiologies of a significant proportions of sporadic corticotropinomas have recently been identified with the discovery of USP8 and USP48 mutations. The elucidation of genetic and molecular pathophysiology in pituitary adenomas is a key factor for better patient management and effective follow-up.