Heterozygous variants in SIX3 and POU1F1 cause pituitary hormone deficiency in mouse and man.

Congenital hypopituitarism is a genetically heterogeneous condition that is part of a spectrum disorder that can include holoprosencephaly. Heterozygous mutations in SIX3 cause variable holoprosencephaly in humans and mice. We identified two children with neonatal hypopituitarism and thin pituitary stalk who were doubly heterozygous for rare, likely deleterious variants in the transcription factors SIX3 and POU1F1. We used genetically engineered mice to understand the disease pathophysiology. Pou1f1 loss-of-function heterozygotes are unaffected; Six3 heterozygotes have pituitary gland dysmorphology and incompletely ossified palate; and the Six3+/-; Pou1f1+/dw double heterozygote mice have a pronounced phenotype, including pituitary growth through the palate. The interaction of Pou1f1 and Six3 in mice supports the possibility of digenic pituitary disease in children. Disruption of Six3 expression in the oral ectoderm completely ablated anterior pituitary development, and deletion of Six3 in the neural ectoderm blocked the development of the pituitary stalk and both anterior and posterior pituitary lobes. Six3 is required in both oral and neural ectodermal tissues for the activation of signaling pathways and transcription factors necessary for pituitary cell fate. These studies clarify the mechanism of SIX3 action in pituitary development and provide support for a digenic basis for hypopituitarism.

High-throughput splicing assays identify missense and silent splice-disruptive POU1F1 variants underlying pituitary hormone deficiency.

Pituitary hormone deficiency occurs in ∼1:4,000 live births. Approximately 3% of the cases are due to mutations in the alpha isoform of POU1F1, a pituitary-specific transcriptional activator. We found four separate heterozygous missense variants in unrelated individuals with hypopituitarism that were predicted to affect a minor isoform, POU1F1 beta, which can act as a transcriptional repressor. These variants retain repressor activity, but they shift splicing to favor the expression of the beta isoform, resulting in dominant-negative loss of function. Using a high-throughput splicing reporter assay, we tested 1,070 single-nucleotide variants in POU1F1. We identified 96 splice-disruptive variants, including 14 synonymous variants. In separate cohorts, we found two additional synonymous variants nominated by this screen that co-segregate with hypopituitarism. This study underlines the importance of evaluating the impact of variants on splicing and provides a catalog for interpretation of variants of unknown significance in POU1F1.

Heterozygous pathogenic variants in POMC are not responsible for monogenic obesity: Implication for MC4R agonist use.

PURPOSE: Recessive deficiency of proopiomelanocortin (POMC) causes childhood-onset severe obesity. Cases can now benefit from the melanocortin 4 receptor agonist setmelanotide. Furthermore, a phase 3 clinical trial is evaluating setmelanotide in heterozygotes for POMC. We performed a large-scale genetic analysis to assess the effect of heterozygous, pathogenic POMC variants on obesity. METHODS: A genetic analysis was performed in a family including 2 cousins with childhood-onset obesity. We analyzed the obesity status of heterozygotes for pathogenic POMC variants in the Human Gene Mutation Database. The association between heterozygous pathogenic POMC variants and obesity risk was assessed using 190,000 exome samples from UK Biobank. RESULTS: The 2 cousins carried a compound heterozygous pathogenic variant in POMC. Six siblings were heterozygotes; only 1 of them had obesity. In Human Gene Mutation Database, we identified 60 heterozygotes for pathogenic POMC variants, of whom 14 had obesity. In UK Biobank, heterozygous pathogenic POMC variants were not associated with obesity risk, but they modestly increased body mass index levels. CONCLUSION: Heterozygous pathogenic POMC variants do not contribute to monogenic obesity, but they slightly increase body mass index. Setmelanotide use in patients with obesity, which would only be based on the presence of a heterozygous POMC variant, can be questioned.

Clinical lessons learned in constitutional hypopituitarism from two decades of experience in a large international cohort.

CONTEXT: The international GENHYPOPIT network collects phenotypical data and screens genetic causes of non-acquired hypopituitarism. AIMS: To describe main phenotype patterns and their evolution through life. DESIGN: Patients were screened according to their phenotype for coding sequence variations in 8 genes: HESX1, LHX3, LHX4, PROP1, POU1F1, TBX19, OTX2 and PROKR2. RESULTS: Among 1213 patients (1143 index cases), the age of diagnosis of hypopituitarism was congenital (24%), in childhood (28%), at puberty (32%), in adulthood (7.2%) or not available (8.8%). Noteworthy, pituitary hormonal deficiencies kept on evolving during adulthood in 49 of patients. Growth Hormone deficiency (GHD) affected 85.8% of patients and was often the first diagnosed deficiency. AdrenoCorticoTropic Hormone deficiency rarely preceded GHD, but usually followed it by over 10 years. Pituitary Magnetic Resonance Imaging (MRI) abnormalities were common (79.7%), with 39.4% pituitary stalk interruption syndrome (PSIS). The most frequently associated extrapituitary malformations were ophthalmological abnormalities (16.1%). Prevalence of identified mutations was 7.3% of index cases (84/1143) and 29.5% in familial cases (n = 146). Genetic analysis in 449 patients without extrapituitary phenotype revealed 36 PROP1, 2 POU1F1 and 17 TBX19 mutations. CONCLUSION: This large international cohort highlights atypical phenotypic presentation of constitutional hypopituitarism, such as post pubertal presentation or adult progression of hormonal deficiencies. These results justify long-term follow-up, and the need for systematic evaluation of associated abnormalities. Genetic defects were rarely identified, mainly PROP1 mutations in pure endocrine phenotypes.

Characterization of the ability of a, second-generation SST-DA chimeric molecule, TBR-065, to suppress GH secretion from human GH-secreting adenoma cells.

CONTEXT: Somatostatin (SST) and dopamine (DA) inhibit growth hormone (GH) secretion and proliferation of GH-secreting pituitary adenomas (GHomas) through binding to SSTR2 and D2R receptors. Chimeric SST-DA compounds (Dopastatins) display increased potency in inhibiting GH secretion, as compared with individual SST or DA analogs (alone or combined). OBJECTIVE: To assess the efficacy of a second-generation dopastatin, TBR-065, in suppressing GH secretion from human GH- and GH/prolactin(PRL)-omas. DESIGN: We compared the ability of TBR-065 to inhibit GH secretion from primary cultures of human GH- or GH/PRLoma cells to that of the first generation dopastatin, TBR-760 (formerly BIM-23A760), octreotide (OCT) and cabergoline (CAB), the later either alone or combined. We investigated whether there was any impact of BIM-133, the metabolite of TBR-065, on the ability of TBR-065 to inhibit GH in these cultures. METHODS: 17 GH- and GH/PRLomas were included in this study. Inhibition of GH secretion by TBR-065, TBR-760, OCT and CAB (0.1 pM to 0.1 µM) was assessed over a period of 8 h. RESULTS: All tumors expressed SSTR2 and D2R mRNAs. GH suppression was higher with TBR-065 as compared with TBR-760 (Emax = 57 ± 5.6% vs. 41.1 ± 12.5%, respectively, p < 0.001) or with OCT + CAB (Emax = 56.8 ± 7.2% vs. 44.4 ± 9.4%, p < 0.001). BIM-133 did not have any impact on the activity of TBR-065. CONCLUSION: TBR-065 has significantly improved efficacy in suppressing GH secretion as compared to current available therapies and may represent a new promising option for the treatment of acromegaly.

Proposition of adjustments to the ACMG-AMP framework for the interpretation of MEN1 missense variants.

In 2015, the ACMG-AMP guidelines provided a general procedure for the objective and reproducible classification of genomic variants. While the benefits of this framework are of major importance, its adaptation for locus-specific use is needed. Multiple Endocrine Neoplasia type 1 (MEN1) occurs due to inactivating mutations in the tumour suppressor gene MEN1, including 20% of missense variants. The classification of these variants may be extremely challenging. Here, we compared the interpretation of the 122 MEN1 missense variants, identified in the French population over the past 15 years by the TENGEN network (French oncogenetics network of neuroendocrine tumors) versus by using the ACMG-AMP guidelines, and analyzed the causes of discordance. A total of 59.8% of missense variants were termed as (likely)-pathogenic variants by TENGEN versus only 28.7% using ACMG-AMP guidelines. Actually, 53.4% (39/73) of TENGEN (likely)-pathogenic variants were declassified in variant of uncertain significance (VUS) by using ACMG-AMP guidelines, thereby affecting the clinical management of patients and their families. Twenty of these ACMG-AMP VUS were found in patients with a clinically authentic MEN1 disease. Here, TENGEN proposes adjustments to the ACMG-AMP framework for the interpretation of MEN1 missense variants. These propositions merge both the classification systems, and are particularly interesting, as MEN1 is included in the ACMG secondary findings list for reporting in clinical genomic sequencing.

Diagnosis and management of congenital hypopituitarism in children.

Hypopituitarism (or pituitary deficiency) is a rare disease with an estimated prevalence of between 1/16,000 and 1/26,000 individuals, defined by insufficient production of one or several anterior pituitary hormones (growth hormone [GH], thyroid-stimulating hormone [TSH], adrenocorticotropic hormone [ACTH], luteinizing hormone [LH], follicle-stimulating hormone [FSH], prolactin), in association or not with diabetes insipidus (antidiuretic hormone [ADH] deficiency). While in adults hypopituitarism is mostly an acquired disease (tumors, irradiation), in children it is most often a congenital condition, due to abnormal pituitary development. Clinical symptoms vary considerably from isolated to combined deficiencies and between syndromic and non-syndromic forms. Early signs are non-specific but should not be overlooked. Diagnosis is based on a combination of clinical, laboratory (testing of all hormonal axes), imaging (brain magnetic resonance imaging [MRI] with thin slices centered on the hypothalamic-pituitary region), and genetic (next-generation sequencing of genes involved in pituitary development, array-based comparative genomic hybridization, and/or genomic analysis) findings. Early brain MRI is crucial in neonates or in cases of severe hormone deficiency for differential diagnosis and to inform syndrome workup. This article presents recommendations for hormone replacement therapy for each of the respective deficient axes. Lifelong follow-up with an endocrinologist is required, including in adulthood, with multidisciplinary management for patients with syndromic forms or comorbidities. Treatment objectives include alleviating symptoms, preventing comorbidities and acute complications, and optimal social and educational integration.

Position statement on the diagnosis and management of congenital pituitary deficiency in adults: The French National Diagnosis and Treatment Protocol (NDTP).

Pituitary deficiency, or hypopituitarism, is a rare chronic disease. It is defined by insufficient synthesis of one or more pituitary hormones (growth hormone, TSH, ACTH, LH-FSH, prolactin), whether or not associated with arginine vasopressin deficiency (formerly known as diabetes insipidus). In adult patients, it is usually acquired (notably during childhood), but can also be congenital, due to abnormal pituitary development. The present study focuses on congenital pituitary deficiency in adults, from diagnosis to follow-up, including special situations such as pregnancy or the elderly. The clinical presentation is highly variable, ranging from isolated deficit to multiple deficits, which may be part of a syndromic form or not. Diagnosis is based on a combination of clinical, biological (assessment of all hormonal axes), radiological (brain and hypothalamic-pituitary MRI) and genetic factors. Treatment consists in hormonal replacement therapy, adapted according to the period of life and the deficits, which may be progressive. Comorbidities, risk of complications and acute decompensation, and the impact on fertility and quality of life all require adaptative multidisciplinary care and long-term monitoring.

Deficient anterior pituitary with common variable immune deficiency (DAVID syndrome): a new case and literature reports.

Deficient anterior pituitary with common variable immune deficiency (DAVID) syndrome is a rare condition characterized by adrenocorticotropic hormone (ACTH) deficiency and primary hypogammaglobulinemia. It is due to heterozygous mutations of the nuclear factor kappa-B subunit 2 (NFKB2) gene. Only a few isolated cases have been reported since its first description by our team. Through the international multicenter GENHYPOPIT network, we identified a new case of DAVID syndrome. We then conducted an extensive review of the DAVID syndrome cases published from 2012 to 2022. A 7-year-old boy was diagnosed with symptomatic hypoglycemia revealing ACTH deficiency. Laboratory tests showed asymptomatic hypogammaglobulinemia. He harbored a heterozygous point mutation in NFKB2 gene (c.2600C > T, p.Ala867Val). His management included hydrocortisone replacement treatment, and he also received subcutaneous immunoglobulins during the Covid-19 pandemic. We analyzed 28 cases of DAVID syndrome with ACTH deficiency. ACTH deficiency was the only hormone deficiency in 79% of patients, but some patients harbored growth hormone (GH) and thyroid stimulating hormone (TSH) deficiencies. The first presenting symptoms were sinus/pulmonary infections (82%, mean age of 3 years) and alopecia (mean age of 4.7 years). ACTH deficiency was the third presenting condition (mean age at diagnosis of 8.6 years). All patients had hypogammaglobulinemia (decreased IgA and IgM levels), and 57% of patients had at least one autoimmune manifestation. Heterozygous mutations at the 3'end of the NFKB2 gene, coding for the C-terminal domain of the protein, were identified in all cases. Better knowledge of DAVID syndrome will help clinicians make an early diagnosis to avoid life-threatening complications.

Balance between somatostatin and D2 receptor expression drives TSH-secreting adenoma response to somatostatin analogues and dopastatins.

CONTEXT: First-line therapy for thyrotropin-secreting pituitary adenomas (TSHomas) is neurosurgery, while medical treatment rests mainly on somatostatin analogues. Clinically available sst(2) -preferring analogues, octreotide and lanreotide, induce normalization of hormone levels in approximately 90% of patients and tumour shrinkage in 45%. OBJECTIVE: We evaluated somatostatin 1, 2, 3 and 5 and dopamine D2 receptor expression in tumour samples from three TSHomas, and the relationships between receptor expression, in vitro antiproliferative response and clinical data, including octreotide test and three months of therapy with octreotide long-acting repeatable (LAR). TSHoma cell proliferation was tested in vitro using octreotide, cabergoline and two chimeric compounds, BIM-23A760 and BIM-23A387. RESULTS: All patients showed significant TSH lowering to acute octreotide test, but a hormonal response to long-term treatment was observed in only two patients, showing a high sst(5) /sst(2) ratio. Patient 2, characterized by high expression of sst(2) and sst(1) and a relative lower expression of sst(5) , experienced tachyphylaxis after prolonged octreotide treatment. In vitro, the somatostatin/dopamine receptor agonist BIM-23A760 caused the highest antiproliferative effect among those tested. Combined treatment with octreotide and cabergoline displayed an additive effect of magnitude comparable to that of the other chimeric compound (BIM-23A387). Octreotide resistance was confirmed in cells isolated from the nonresponder patient, although it could be overcome by treatment with the chimeric compounds. CONCLUSIONS: A high sst(5) /sst(2) ratio might be predictive of a positive outcome to long-term treatment with somatostatin analogues in TSHomas. Moreover, combined somatostatin and D(2) receptor targeting might be considered as a potential tool to improve the response rate in octreotide-resistant tumours.

Unilateral agenesis of internal carotid artery associated with congenital combined pituitary hormone deficiency and pituitary stalk interruption without HESX1, LHX4 or OTX2 mutation: a case report.

Agenesis of internal carotid artery (ICA) is an unusual finding in subjects with congenital Combined Pituitary hormone deficiency (CPHD) with only nine cases being reported to date but to our best knowledge none of them was genetically investigated. A 10-years old girl presented with severe growth failure (height 103 cm) with substantial bone age delay (3 years). She had no history of perinatal insults or familial CPHD. There was no evidence of mental retardation or craniofacial dysmorphism or ophtalmological abnormalities. She was first diagnosed with GH and TSH deficiency. Cerebral magnetic resonance imaging (MRI) showed hypoplastic anterior pituitary, flat sella turcica, absent pituitary stalk with ectopic posterior pituitary as well as agenesis of the left ICA and the left carotid canal. Genomic analysis of pituitary transcription factor HESX1, LHX4 and OTX2 showed no mutations. Treatment with GH and thyroxine was started. The patient remained free of neurovascular symptoms for 5 years but she presented at the age of 15 years with delayed puberty related to an evolving gonadotropin deficiency. ICA agenesis associated with CPHD is unusual and is often asymptomatic in children. Since the CPHD with pituitary stalk interruption cannot be due to HESX1, LHX4 or OTX2 mutation in our case, other pathogenetic mechanisms may be responsible for CPHD associated with unilateral ICA agenesis.

Congenital Central Hypothyroidism Caused by a Novel IGSF1 Variant Identified in a French Family.

INTRODUCTION: Congenital central hypothyroidism (CCH) is a rare disorder that can be caused by X-linked mutations in the immunoglobulin superfamily member 1 (IGSF1) gene. Here, we describe four familial cases with a variable presentation due to a novel IGSF1 pathogenic variant. CASE PRESENTATION: In the index case, an investigation at birth of a suspected brain-lung-thyroid syndrome surprisingly revealed a central hypothyroidism. Next-generation sequencing uncovered a novel IGSF1 pathogenic variant: a hemizygous single base duplication (G) resulting in a premature stop codon (NM_001555.4: c.2485dup, p.Ala829Glyfs*15). Further family investigations revealed missed neonatal CCH for the older brother who presented with prolonged jaundice (thyroid stimulating hormone 3.06 mUI/L, FT4 9.4 pmol/L, FT3 4.2 pmol/L). It also led to the diagnosis of CCH at 11 months of age for the younger brother, whose thyroid function was considered normal at birth. Neuropsychological evaluations showed no cognitive impairment for the eldest two brothers, but a slightly reduced processing-speed index compared with the other parameters for the oldest. Furthermore, a maternal uncle was diagnosed with biochemical CCH at 34 years of age, despite having few symptoms, and a complete workup revealed prolactin deficiency and macroorchidism. DISCUSSION: This report of a rare case of neonatal CCH caused by IGSF1 deficiency highlights the importance of recognizing the neonatal signs of hypothyroidism to diagnose CCH as early as possible. Our results also show the importance of performing family genetic screening if a pathogenic variant is identified, to properly monitor carriers as CCH may develop over time. We suggest that these families should be followed up in the long term to better understand the natural history of this syndrome and evaluate the need for hormone substitution.

A novel TBX19 gene mutation in patients with isolated ACTH deficiency from distinct families with a common geographical origin.

Isolated ACTH deficiency (IAD) is a life-threatening condition, particularly in the neonatal period, while a main consequence of undiagnosed isolated ACTH deficiency in survivors is cognitive impairment. TBX19 is involved in the differentiation and proliferation of corticotropic cells and TBX19 mutations are responsible for more than 60% of neonatal cases of IAD. We describe a new variant of the main TBX19 transcript (NM 005149.3, c.840del (p.(Glu280Asp fs*27)), classified as pathogenic, whose pathogenicity is assumed to be due to nonsense mediated decay leading to non-expression of T-box transcription factor TBX19. Moreover we summarize the TBX19 mutations published as individual cases since our last large cohort. Interestingly, this pathogenic variant was identified in four patients from three apparently unrelated families. Two of these families were consanguineous, and after investigations all of three were discovered to have roots in the same mountainous region of northern Morocco, suggesting a founder effect. Early diagnosis, timely treatment (hydrocortisone therapy) and preventive education allowed normal development, growth and quality of life in all patients.

IGSF1 mutations are the most frequent genetic aetiology of thyrotropin deficiency.

Design: Thyroid-stimulating hormone deficiency (TSHD) is a rare disease. It may be isolated, secondary to abnormalities of genes involved in TSH biosynthesis, or associated with other pituitary deficits or abnormalities of genes involved in pituitary ontogenesis. Several genes are involved in thyrotroph development and function. Objective: Our aim was to determine the genetic causes of TSHD, either isolated (ITSHD) or associated with somatotroph deficiency (TSHD-GHD), in the cohort of patients from the GENHYPOPIT network. Methods: Next-generation sequencing (NGS) analyses were performed as a panel of genes on a cohort of patients with non-syndromic ITSHD or TSHGHD. The variants were classified according to the American College of Medical Genetics classification reviewed by the NGS-Diag network and correlated with the phenotype. Class 3, 4, and 5 single-nucleotide variants were checked by Sanger sequencing and copy number variants by multiplex ligation-dependent probe amplification (MLPA). Results: A total of 64 index cases (22 ITSHD and 42 TSHD-GHD) were included in this cohort. A genetic cause was identified in 26.5% of patients, with 36.3% in the ITSHD group (variants in TSHß and IGSF1) and 21.4% in TSHD-GHD (variants in IGSF1, TSHß, TRHR, GH1, POU1F1, and PROP1). Among the pathogenic and likely pathogenic variants identified, 42% were in IGSF1, including six not previously reported. Conclusion: Our results show that IGSF1 variants represent the most frequent aetiology of TSH deficiency. Despite a systematic NGS approach and the identification of new variants, most patients remain without a molecular diagnosis. Larger scale studies, such as exome or genome studies, should be considered in the future.

Detection of genetic hypopituitarism in an adult population of idiopathic pituitary insufficiency patients with growth hormone deficiency.

Idiopathic pituitary insufficiency (IPI) is diagnosed in 10% of all hypopituitary patients. There are several known and unknown aetiologies within the IPI group. The aim of this study was to investigate an adult IPI population for genetic cause according a screening schedule. From files of 373 GH deficient (GHD) patients on GH replacement 50 cases with IPI were identified. Of the 39 patients that approved to the study, 25 patients were selected for genetic investigation according to phenotype and 14 patients were not further tested, as sporadic isolated GHD (n = 9) and GHD with diabetes insipidus (n = 5) have low probability for a known genetic cause. Genotyping of all coding exons of HESX1, LHX4, PROP1, POU1F1 and GH1 genes were performed according to a diagnostic algorithm based on clinical, hormonal and neuroradiological phenotype. Among the 25 patients, an overall rate of 8% of mutations was found, and a 50% rate in familial cases. Among two sibling pairs, one pair that presented with complete anterior pituitary insufficiency, had a compound heterozygous PROP1 gene mutation (codons 117 and 120: exon 3 p Phe 117 Ile (c349 T>A) and p Arg 120 Cys (c358 C>T)) with a phenotype of very late onset ACTH-insufficiency. In the other sibling pair and in the sporadic cases no mutation was identified. This study suggests that currently known genetic causes are rare in sporadic adult IPI patients, and that systematic genetic screening is not needed in adult-onset sporadic cases of IPI. Conversely, familial cases are highly suspect for genetic causes.

In vivo and in vitro response to octreotide LAR in a TSH-secreting adenoma: characterization of somatostatin receptor expression and role of subtype 5.

Thyrotropin-secreting pituitary adenomas (TSHomas) are a rare cause of hyperthyroidism and account for less than 2% of pituitary adenomas. Medical therapy with somatostatin analogues (SSAs) effectively reduces TSH secretion in approximately 80% of patients and induces shrinkage in about 45% of tumors. According with previous data, resistance to SSA treatment might be due to heterogeneity in somatostatin receptors (SSTRs) expression. We report the case of TSHoma in a 41-year-old man treated with octreotide LAR that caused a dramatic decrease of TSH and thyroid hormones and tumor shrinkage already after 3 months of pre-surgical therapy. In search of potential molecular determinants of octreotide effectiveness, we measured, in primary cultures from this tumor, SSTR and dopamine D2 receptor (D2R) expression, and octreotide and/or cabergoline effects on TSH secretion and cell proliferation. SSTR5 and D2R expression was higher than SSTR2. Octreotide significantly inhibited TSH secretion more effectively than cabergoline (P<0.001), whereas the combined treatment was comparable with cabergoline alone. Similarly, octreotide resulted more effective than cabergoline on cell proliferation, while the combination did not show any additive or synergistic effects. In conclusion, the significant antisecretive and antiproliferative effect of octreotide in this patient might be related to the high expression of SSTR5, in the presence of SSTR2. After reviewing the literature, indeed, in line with previous observations, we hypothesize that SSTR5/SSTR2 ratio in TSHomas may represent a useful marker in predicting the outcome of therapy with SSAs. The role of D2R should be further explored considering that the presence of D2R can influence SSTRs functionality.

Hypopituitarism in Patients with Blepharophimosis and FOXL2 Mutations.

BACKGROUND: FOXL2 is the gene involved in blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES). There have been few single case reports of growth hormone deficiency (GHD) with this syndrome, and Foxl2 is known to be involved in pituitary development in mice. Our aim was to analyze the prevalence of FOXL2 gene alteration in a series of patients with congenital hypopituitarism and eyelid anomalies. METHODS: FOXL2 was analyzed in 10 patients with hypopituitarism (ranging from isolated GHD to complete pituitary hormone deficiency) and eyelid anomalies (typical BPES in 4 patients and milder anomalies in 6 patients). In patients with an FOXL2 mutation, we ruled out other possible molecular explanations by analyzing a panel of 20 genes known to be associated with hypopituitarism, and a candidate gene approach was used for patients without an FOXL2mutation. RESULTS: Three patients had an FOXL2mutation. All 3 had typical BPES. Their pituitary phenotype varied from GHD to complete pituitary hormone deficiency and their pituitary morphology ranged from normal to an interrupted pituitary stalk. No mutations were found in genes previously associated with hypopituitarism. CONCLUSION: Our study shows that some patients with BPES have hypopituitarism with no molecular explanation other than FOXL2 mutation. This points toward an involvement of FOXL2 in human pituitary development.

Germinal defects of SDHx genes in patients with isolated pituitary adenoma.

BACKGROUND: The '3PAs' syndrome, associating pituitary adenoma (PA) and pheochromocytoma/paraganglioma (PPGL), is sometimes associated with mutations in PPGL-predisposing genes, such as SDHx or MAX. In '3PAs' syndrome, PAs can occur before PPGL, suggesting a new gateway into SDHx/MAX-related diseases. OBJECTIVE: To determine the SDHx/MAX mutation prevalence in patients with isolated PAs and characterize PAs of patients with SDHx/MAX mutations. DESIGN: Genes involved in PAs (AIP/MEN1/CDKN1B) or PPGLs (SDHx/MAX) were sequenced in patients with isolated PAs. We then conducted a review of cases of PA in the setting of '3PAs' syndrome. RESULTS: A total of 263 patients were recruited. Seven (likely) pathogenic variants were found in AIP, two in MEN1, two in SDHA, and one in SDHC. The prevalence of SDHx mutations reached 1.1% (3/263). Of 31 reported patients with PAs harboring SDHx/MAX mutations (28 published cases and 3 cases reported here), 6/31 (19%) developed PA before PPGL and 8/31 (26%) had isolated PA. The age of onset was later than in patients with AIP/MEN1 mutations. PAs were mainly macroprolactinomas and showed intracytoplasmic vacuoles seen on histopathology. CONCLUSIONS: We discovered SDHx mutations in patients bearing PA who had no familial or personal history of PPGL. However, the question of incidental association remains unresolved and data to determine the benefit of SDHx/MAX screening in these patients are lacking. We recommend that patients with isolated PA should be carefully examined for a family history of PPGLs. A family history of PPGL, as well as the presence of intracytoplasmic vacuoles in PA, requires SDHx/MAX genetic testing of patients.

Somatostatin-dopamine ligands in the treatment of pituitary adenomas.

Somatostatin receptors (sst1-5) and dopamine receptor 2 (D2DR) are well expressed and co-localized in several human pituitary adenomas, suggesting possible functional interactions in the control of hormonal hypersecretion and tumor cell growth. The present review describes the expression and functionality of these receptors in the different classes of human pituitary adenomas. The sst2 agonists, octreotide and lanreotide, control GH hypersecretion and tumor growth in about 65% of somatotropinomas. The D2DR agonists, bromocriptine and cabergoline, control about 90% of prolactinomas. Such drugs are much less effective in the control of the others pituitary adenomas also expressing ssts and D2DR receptors. The second part summarizes the current knowledge on new chimeric compounds with sst2, sst5, and D2DR affinity. Such ligands bearing distinct ssts and DRD2 pharmacophores may synergistically produce an increased control of secretion and/or of proliferation in the different types of pituitary adenomas. The mechanisms of action of such chimeric molecules through increased binding affinities, prolonged bioavailability, ligand-induced modulation of receptors heterodimerization, are discussed.

DIAGNOSIS OF ENDOCRINE DISEASE: Pituitary stalk interruption syndrome: etiology and clinical manifestations.

Pituitary stalk interruption syndrome (PSIS) is a congenital pituitary anatomical defect. This syndrome is an antenatal developmental defect belonging to the holoprosencephaly phenotype spectrum. It is heterogeneous regarding clinical, biological and radiological presentation and is characterized by the following triad: thin (<1 mm) or interrupted pituitary stalk connecting the hypothalamus to the pituitary gland, no eutopic posterior lobe, and hypoplasia or aplasia of the anterior lobe. This review reports current knowledge about the composite pathogenesis, for which underlying mechanisms remain unclear. Current data suggest genetic origins involving early developmental gene mutations with complex inheritance patterns and environmental influence, placing PSIS at the crossroads between Mendelian and multifactorial diseases. The phenotype associated with PSIS is highly heterogeneous with a high incidence of various combinations of hormonal deficiencies, sometimes associated with extra-pituitary birth defects. The age at onset is variable, but typical presentation is evolutive combined anterior pituitary hormone deficiencies at pediatric age, which progress even during adulthood to panhypopituitarism. Therefore, patients' follow-up throughout life is essential for adequate management.