Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant disorder characterized by the occurrence of combined tumors in different glands, usually the parathyroid, pancreas and pituitary, as well as in other parts of the digestive tract. The present study describes the phenotype of a Brazilian family with MEN1 caused by a previously unreported MEN1 gene mutation.

We report the case of a 41-year-old male, the proband, who presented with angiofibromas, primary hyperparathyroidism, macroprolactinoma, and pancreatic neuroendocrine tumor. Next generation sequencing analysis of the MEN1 gene in the patient's peripheral blood DNA sample revealed a deletion of 16 base pairs (c.1366-12_1369del;p) resulting in a framing error. Additional 5 members of the family (4 brothers and a first cousin) presented with clinical features of MEN1. All brothers underwent mutation screening and tested positive for the same genetic variant. Two of them were also diagnosed with papillary thyroid carcinoma.

The c.1366-12_1369del;p mutation is located between the 10th and last exon of the MEN 1 gene and it's preceding intron, encompassing the canonical sites in the splice junction. The 10th exon of MEN1, possibly lost with this variant, encodes the last 163 amino acids that compose the Menin protein's C-terminal region, which harbors nuclear localization signals essential for its internalization into the nuclear compartment and interaction with the nuclear matrix.

Our case reports add to the literature the description of a new pathogenic variant of the MEN 1 gene.

Pancreatic neuroendocrine tumors (PNETs) are the leading cause of death related to multiple endocrine neoplasia type 1 (MEN1). Previous studies have linked certain mutations in the MEN1 gene and loss of interactions with MENIN's functional partners to the mortality or aggressiveness of PNETs. This study aimed to evaluate the genotype-phenotype correlations of MEN1-related PNETs in Korean patients and to summarize the treatment outcomes comprehensively.

We retrospectively analyzed 72 patients diagnosed with MEN1 at a tertiary care center in Korea between January 2003 and September 2022. MEN1 mutations were analyzed using direct or next-generation sequencing.

Among 40 families with MEN1, 10 had exon 2 mutations, which were the most frequently observed. Of these, 50 (69.4 %) were diagnosed with PNETs; 20 underwent pancreatic resection. Patients with truncating mutations showed a significant difference in age-related penetrance of PNET (p = 0.029). No distinct genotype was associated with malignant transformation (lymph node or distant metastasis) in MEN1-related PNETs. In the subgroup Cox model, mutations in exons 3 or 10 showed significant differences in tumor progression in the observation group (adjusted hazard ratio: 8.164,(95 % CI: 1.648-40.436), p = 0.010, HR: 8.300, (95 % CI: 1.808-38.113), p = 0.007).

PNETs in Korean patients with MEN1 exhibit a stable prognosis. An individualized follow-up strategy may be necessary, particularly for young patients with truncating mutation in the MEN1 gene. In addition, those with mutations in exons 3 or 10 may require more active surveillance to decrease the risk of progression.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal-dominant disorder characterized by tumors of the pituitary, parathyroid, and endocrine-gastrointestinal tract. Pituitary neuroendocrine tumors (PitNETs) occur in about 40% of MEN1 cases, with 10% being the first manifestation. Recent studies show a slight female predominance, with microPitNETs (<1 cm) being more common than macroPitNETs (>1 cm). Functional PitNETs (FPitNETs) are more frequent than non-functional ones (36% to 48%), with prolactinomas being the most common FPitNETs. MEN1-associated PitNETs are often plurihormonal, larger, and more invasive compared to sporadic types, though patient age and FPitNET proportions are similar. MEN1 mutation-negative patients tend to have larger, symptomatic PitNETs at diagnosis. Six patients with MEN1 have been reported to have pituitary carcinomas, including a mutation- negative patient. Treatment approach between PitNETs in MEN1 and sporadic types appears to be similar. PitNETs also occur in MEN4, but their epidemiology is less understood. In patients with a MEN1-like phenotype and negative genetic testing, MEN4 should be considered.

Multiple endocrine neoplasia type 1 (MEN-1) is a syndrome characterized by development of tumors including parathyroid adenomas, duodenopancreatic neuroendocrine tumors, and pituitary adenomas. We describe 1 patient with a novel and another with a rare pathogenic MEN-1 variant. Case 1 was a 61-year-old woman with recurrent hypercalcemia who ultimately required a subtotal parathyroidectomy, with a thymectomy revealing a thymoma. She then developed a gastrinoma requiring pancreatectomy and also had a biochemically nonfunctioning sellar mass. Genetic testing found a novel MEN1:c.1192delC, p.(Gln398Argfs*47) pathogenic variant. Case 2 was a 38-year-old woman with a family history of MEN-1, who had recurrent hypercalcemia and nephrolithiasis requiring a subtotal parathyroidectomy. She had a macroprolactinoma, but no pancreatic lesions. Genetic testing found a rare MEN1:c.784-9G > A pathogenic variant. MEN-1 syndrome should be considered in patients presenting with 1 or more classical MEN-1-associated tumors based on clinical suspicion.

Multiple endocrine neoplasia type 1 (MEN1) syndrome is an autosomal dominant disorder caused by a germline pathogenic variant in the MEN1 tumor suppressor gene. Patients with MEN1 have a high risk for primary hyperparathyroidism (PHPT) with a penetrance of nearly 100%, pituitary adenomas (PitAd) in 40% of patients, and neuroendocrine neoplasms (NEN) of the pancreas (40% of patients), duodenum, lung, and thymus. Increased MEN1-related mortality is mainly related to duodenal-pancreatic and thymic NEN. Management of PHPT differs from that of patients with sporadic disease, as the surgical approach in MEN1-related PHPT includes near-total or total parathyroidectomy because of multigland hyperplasia in most patients and the consequent high risk of recurrence. NEN management also differs from patients with sporadic disease due to multiple synchronous and metasynchronous neoplasms. In addition, the lifelong risk of developing NEN requires special considerations to avoid excessive surgeries and to minimize damage to the patient's function and well-being. This progress report will outline current insights into surveillance and management of the major clinical manifestation of MEN1 syndrome in children and adults with MEN1 diagnosis. In addition, we will discuss MEN1-like clinical presentation with negative MEN1-genetic workup and future clinical and research directions.

Adrenocortical tumors (ACTs) are frequently encountered in clinical practice. They vary in clinical and biological characteristics from nonfunctional to life threatening hormone excess, from benign to highly aggressive malignant tumors. Most ACTs appear to be benign and nonfunctioning. It has been controversial how these apparently benign and nonfunctioning tumors should be monitored. Over the past few decades, significant advances have been made in understanding the regulation of growth and tumorigenesis in adrenocortical cells. Defining the molecular pathomechanisms in inherited tumor syndromes led to the expansion of research to sporadic ACTs. Distinct molecular signatures have been identified in sporadic ACTs and a potential genomic classification of ACT has been proposed.

In this review, we discuss the various adrenocortical pathologies associated with hereditary syndromes with special focus on their molecular pathomechanisms, the understanding of which is important in the era of precision medicine.

Identifying the molecular pathomechanisms of the adrenocortical tumorigenesis in inherited syndromes has led to the understanding of the alterations in different signaling pathways that help explain the wide variations in the biology and behavior of ACTs.

The genetic landscape of corticotroph tumours of the pituitary gland has dramatically changed over the last 10 years. Somatic changes in the USP8 gene account for the most common genetic defect in corticotrophinomas, especially in females, while variants in TP53 or ATRX are associated with a subset of aggressive tumours. Germline defects have also been identified in patients with Cushing's disease: some are well-established (MEN1, CDKN1B, DICER1), while others are rare and could represent coincidences. In this review, we summarise the current knowledge on the genetic drivers of corticotroph tumorigenesis, their molecular consequences, and their impact on the clinical presentation and prognosis.

Aim: Pancreatic Neuroendocrine tumors (pNETs) are a heterogeneous group of neoplasms whose tumor biology is still little known. Thanks to next-generation sequencing, pathogenic mutations in base-excision-repair MUTYH gene and homologous recombination genes CHEK2 and BRCA2 seem to have a role in the development of pNETs.Research design & methods: We assumed that Homologous Recombination Deficiency (HRD) could be a critical pathogenetic mechanism for pNETs. We evaluated the HR status in a case series of 33 patients diagnosed with pNET at the Modena Cancer Center using the AmoyDX HRD Focus assay.Results: The AmoyDx test did not identify any HRD-positive patients (median GSS equal to 1.1, positive score: >50), and no pathogenic BRCA variants were detected. However, thanks to the SNP analysis, a consistent number of partial or complete single-copy deletions or duplications in several chromosomes.Conclusion: The AmoyDX HRD focus assay performed well on pancreatic samples, despite being originally designed for ovarian cancer and used on samples stored for over a year. Larger studies are needed to further assess the role of HRD assays in pNETs research.

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary tumor syndrome characterized by endocrine tumors, typically from parathyroid, pancreatic, or anterior pituitary origin. In addition, benign cutaneous soft tissue tumors are prevalent in MEN1 patients. Although sarcomas have been reported in MEN1 patients it is unclear if these tumors should be considered as part of the MEN1 syndrome. Here, five patients with a MEN1 syndrome and a sarcoma are described. In all five sarcomas loss of heterozygosity of the MEN1 gene and loss of expression of menin are shown, suggesting that sarcomas may be a phenotypic expression of MEN1 syndrome.

Primary hyperparathyroidism represents the third most prevalent endocrine disease in the general population, consisting of an excessive secretion of parathyroid hormone from one or, more frequently, more of the parathyroid glands, leading to a dysregulation of calcium homeostasis. Schematically, its development occurs primarily by pathophysiological events with genetic mutation, at the germline and/or somatic level, that favor the neoplastic transformation of parathyroid cells and promote their aberrant proliferation, and mutations determining the shift in the PTH "set-point", thus interfering with the normal pathways of PTH secretion and leading to a "resetting" of Ca2+-dependent PTH secretion or to a secretion of PTH insensitive to changes in extracellular Ca2+ levels. Familial syndromic and non-syndromic forms of primary hyperparathyroidism are responsible for approximately 2-5% of primary hyperparathyroidism cases and most of them are inherited forms. The history of the genetic/molecular studies of parathyroid tumorigenesis associated with multiple endocrine neoplasia type 1 syndrome (MEN1) represents an interesting model to understand genetic-epigenetic-molecular aspects underlying the pathophysiology of primary hyperparathyroidism, both in relation to syndromic and non-syndromic forms. This minireview aims to take a quick and simplified look at the MEN1-associated parathyroid tumorigenesis, focusing on the molecular underlying mechanisms. Clinical, epidemiological, and observational studies, as well as specific guidelines, molecular genetics studies, and reviews, have been considered. Only studies submitted to PubMed in the English language were included, without time constraints.

Multiple endocrine neoplasia (MEN) is a group of rare genetic diseases characterized by the occurrence of multiple tumors of the endocrine system in the same patient. The first MEN described was MEN1, followed by MEN2A, and MEN2B. The identification of the genes responsible for these syndromes led to the introduction of family genetic screening programs. More than twenty years later, not all cases of MENs have been resolved from a genetic point of view, and new clinicogenetic entities have been described. In this review, we will discuss the strategies and difficulties of genetic screening for classic and newly described MENs in a clinical setting, from limitations in sequencing, to problems in classifying variants, to the identification of new candidate genes. In the era of genomic medicine, characterization of new candidate genes and their specific tumor risk is essential for inclusion of patients in personalized medicine programs as well as to permit accurate genetic counseling to be proposed for families.

Multiple Endocrine Neoplasia type 1 (MEN1) is a rare genetic disease, characterized by co-occurrence of several lesions of the endocrine system. In MEN1, the pathogenic MEN1 gene mutations lead to the Abnormal expression of menin, a critical tumor suppressor protein. We here reported a case of a 14-year-old male with insulinoma and primary hyperparathyroidism. Genetic testing demonstrated a novel heterozygote variant c.587delA of MEN1, resulting in the substitution of the 196th amino acid, changing from glutamic acid to glycine, followed by a frameshift translation of 33 amino acids. An identical variant was identified in the proband's father, who was further diagnosed with hyperparathyroidism. To the best of our knowledge, this is the first report of MEN1 syndrome caused by the c.587delA MEN1 variant. Observations indicated that, despite sharing the same MEN1 gene change, family members exhibited diverse clinical phenotypes. This underscored the presence of genetic anticipation within the familial context.

Multiple endocrine neoplasia (MEN) syndromes are part of a spectrum of clinically well-defined tumor syndromes ultimately characterized by histologically similar tumors arising in patients and families with mutations in one of the following four genes: MEN1, RET, CDKN1B, and MAX. The high level of genetic and phenotypic heterogeneity has been linked to phenocopies and modifying genes, as well as unknown mechanisms that might be investigated in the future based on preclinical and translational considerations. MEN1, also known as Wermer's syndrome (OMIM *131100), is an autosomal dominant syndrome codifying for the most frequent MEN syndrome showing high penetrance due to mutations in the MEN1 gene; nevertheless, clinical manifestations vary among patients in terms of tumor localization, age of onset, and clinical aggressiveness/severity, even within the same families. This has been linked to the effect of modifying genes, as described in the review. MEN 2-2b-4 and 5 also show remarkable clinical heterogeneity. The traditional view of genetically predisposing monogenic or multifactorial disorders is no longer valid, and mandates a change in scientific focus. Phenotypes are indeed rarely consistent across genetic backgrounds and environments. In the future, understanding factors and genetic variants that control cellular functions and the expression of disease genes should provide insights into fundamental disease processes, providing implications for counseling and therapeutic and prophylactic possibilities.

MEN1 is a rare syndrome caused by mutations in the MEN1 gene. We describe a clinical case of MEN1 syndrome associated with a recently discovered pathogenic mutation of MEN1 gene. A 32-year-old man with a history of osteopenia, nephrolithiasis, hypercalcemia and hypophosphatemia, impaired fasting glucose, and asthenia was admitted to our outpatient unit. Primary hyperparathyroidism, sustained by three hyperplastic parathyroid glands, was diagnosed. Prolactin- and GH-secreting adenomas were ruled out. After undergoing subtotal parathyroidectomy, the patient was diagnosed with non-functioning pituitary adenoma, three pancreatic lesions, and Cushing syndrome sustained by left adrenal adenoma. The patient underwent left adrenal surgery; somatostatin analogue lanreotide was started for the pancreatic lesions; the pituitary adenoma, being small and non-secreting, was not treated. A genetic test was performed to confirm the diagnosis of MEN1 syndrome, finding an association with a recently discovered mutation: the (NM_130799.2):c.758delC (p.Ser253Cysfs*28) in exon 4.

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary endocrine syndrome caused by pathogenic variants in MEN1 tumor suppressor gene. Diagnosis is commonly based on clinical criteria and confirmed by genetic testing. The objective of the present study was to report on a MEN1 case characterized by multiple pancreatic glucagonomas, with particular concern on the possible predisposing genetic defects.

While conducting an extensive review of the most recent scientific evidence on the unusual glucagonoma familial forms, we analyzed the MEN1 gene in a 35-year-old female with MEN1, as well as her son and daughter, using Sanger and next-generation sequencing (NGS) approaches. We additionally explored the functional and structural consequences of the identified variant using in silico analyses.

NGS did not show any known pathogenic variant in the tested regions. However, a new non-conservative variant in exon 4 of MEN1 gene was found in heterozygosity in the patient and in her daughter, resulting in an amino acid substitution from hydrophobic cysteine to hydrophilic arginine at c.703T > C, p.(Cys235Arg). This variant is absent from populations databases and was never reported in full papers: its characteristics, together with the high specificity of the patient's clinical phenotype, pointed toward a possible causative role.

Our findings confirm the need for careful genetic analysis of patients with MEN1 and establish a likely pathogenic role for the new p.(Cys235Arg) variant, at least in the rare subset of MEN1 associated with glucagonomas.

Pancreatic neuroendocrine tumors (PanNETs) and lung NETs (LNETs) represent a rare but clinically significant subgroup of neoplasms. While the majority is sporadic, approximately 17% of PanNETs and a subset of LNETs develop in the context of monogenic familial tumor syndromes, especially multiple endocrine neoplasia type 1 (MEN1) syndrome. Other inherited syndromes associated with PanNETs include MEN4, von Hippel-Lindau (VHL) syndrome, neurofibromatosis type 1 (NF1), and tuberous sclerosis complex (TSC). These syndromes are highly penetrant and their clinical manifestations may vary even among members of the same family. They are attributed to genetic mutations involving key molecular pathways regulating cell growth, differentiation, and angiogenesis. Pancreatic NETs in hereditary syndromes are often multiple, develop at a younger age compared to sporadic tumors, and are associated with endocrine and nonendocrine tumors derived from multiple organs. Lung NETs are not as common as PanNETs and are mostly encountered in MEN1 syndrome and include typical and atypical lung carcinoids. Early detection of PanNETs and LNETs related to inherited syndromes is crucial, and specific follow-up protocols need to be employed to optimize diagnosis and management. Genetic screening is recommended in childhood, and diagnostic screening starts often in adolescence, even in asymptomatic mutation carriers. Optimal management and therapeutic decisions should be made in the context of a multidisciplinary team in specialized centers, whereas specific biomarkers aiming to identify patients denoted to follow a more aggressive course need to be developed.

Primary hyperparathyroidism with parathyroid tumors is a typical manifestation of Multiple Endocrine Neoplasia Type 1 (MEN1) and is historically termed "primary hyperplasia". Whether these tumors represent a multi-glandular clonal disease or hyperplasia has not been robustly proven so far. Loss of Menin protein expression is associated with inactivation of both alleles and a good surrogate for a MEN1 gene mutation. The cyclin-dependent kinase inhibitor 1B (CDKN1B) gene is mutated in MEN4 and encodes for protein p27 whose expression is poorly studied in the syndromic MEN1 setting.Here, we analyzed histomorphology and protein expression of Menin and p27 in parathyroid adenomas of 25 patients of two independent, well-characterized MEN1 cohorts. The pattern of loss of heterozygosity (LOH) was assessed by fluorescence in situ hybridization (FISH) in one MEN1-associated parathyroid adenoma. Further, next-generation sequencing (NGS) was performed on eleven nodules of four MEN1 patients.Morphologically, the majority of MEN1 adenomas consisted of multiple distinct nodules, in which Menin expression was mostly lost and p27 protein expression reduced. FISH analysis revealed that most nodules exhibited MEN1 loss, with or without the loss of centromere 11. NGS demonstrated both subclonal evolution and the existence of clonally unrelated tumors.Syndromic MEN1 parathyroid adenomas therefore consist of multiple clones with subclones, which supports the current concept of the novel WHO classification of parathyroid tumors (2022). p27 expression was lost in a large fraction of MEN1 parathyroids and must therefore be used with caution in suggesting MEN4.

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. Genetic tests should be part of the approach to patients with acromegaly and gigantism because they can refine the clinical diagnoses, opening the possibility to tailor the clinical conduct to each patient. Even more, genetic testing and clinical screening of at-risk individuals have a positive impact on disease outcomes, by allowing for the timely detection and treatment of somatotrophinomas at early stages. Future research should focus on determining the actual frequency of novel genetic drivers of somatotrophinomas in the general population, developing up-to-date disease-specific multi-gene panels for clinical use, and finding strategies to improve access to modern genetic testing worldwide.

Tall stature is defined as height greater than the threshold of more than 2 standard deviations above the average population height for age, sex, and ethnicity. Many studies have described the main aspects of this condition during puberty, but an analysis of the characteristics that the physician should consider in the differential diagnosis of gigantism-tall stature secondary to a pituitary tumour-during the transition age (15-25 years) is still lacking.

A comprehensive search of English-language original articles was conducted in the MEDLINE database (December 2021-March 2022). We selected all studies regarding epidemiology, genetic aspects, and the diagnosis of tall stature and gigantism during the transition age.

Generally, referrals for tall stature are not as frequent as expected because most cases are familial and are usually unreported by parents and patients to endocrinologists. For this reason, lacking such experience of tall stature, familiarity with many rarer overgrowth syndromes is essential. In the transition age, it is important but challenging to distinguish adolescents with high constitutional stature from those with gigantism. Pituitary gigantism is a rare disease in the transition age, but its systemic complications are very relevant for future health. Endocrine evaluation is crucial for identifying conditions that require hormonal treatment so that they can be treated early to improve the quality of life and prevent comorbidities of individual patient in this age range.

The aim of our review is to provide a practical clinical approach to recognise adolescents, potentially affected by gigantism, as early as possible.

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant syndrome caused by inactivating pathogenic variants in the tumor suppressor gene menin 1 on chromosome 11q13 (Falchetti et al., 2009). The syndrome is characterized by neoplasia in two or more endocrine glands and has a high degree of penetrance. Pathogenic germline multiple neoplasia type 1 variants primarily result in neoplasia affecting the parathyroid glands, the pancreatic islet cells, and the anterior pituitary in combination. Primary hyperparathyroidism is the most common pathological manifestation of the syndrome, followed by pancreatic neuroendocrine tumors. Important genetic confirmation has been provided showing that ependymoma should be considered as a neoplasm that can occur in patients with MEN1 (Kato et al., 1996; Cuevas-Ocampo et al., 2017). The biphasic histopathological tumor entity shown in the present case we name Pleomorphic Xanthoastocytoma grade 3 differential pathology (PDP) in association with Multiple Endocrine Neoplasia type 1. This MEN1 associated tumor subtype is an extension of the findings on MEN1 associated ependymoma, where we show that the clinical phenotype itself may potentially be triggered by a frameshift germline pathogenic variant for the MEN1 gene, in combination with cyclin-dependent kinase inhibitor 1B gene germline variant and cyclin dependent kinase inhibitor 2A somatic deletion downstream of menin.

Primary hyperparathyroidism (PHPT), a relatively common disorder characterized by hypercalcemia with raised or inappropriately normal serum parathyroid hormone (PTH) concentrations, may occur as part of a hereditary syndromic disorder or as a non-syndromic disease. The associated syndromic disorders include multiple endocrine neoplasia types 1-5 (MEN1-5) and hyperparathyroidism with jaw tumor (HPT-JT) syndromes, and the non-syndromic forms include familial hypocalciuric hypercalcemia types 1-3 (FHH1-3), familial isolated hyperparathyroidism (FIHP), and neonatal severe hyperparathyroidism (NS-HPT). Such hereditary forms may occur in > 10% of patients with PHPT, and their recognition is important for implementation of gene-specific screening protocols and investigations for other associated tumors. Syndromic PHPT tends to be multifocal and multiglandular with most patients requiring parathyroidectomy with the aim of limiting end-organ damage associated with hypercalcemia, particularly osteoporosis, nephrolithiasis, and renal failure. Some patients with non-syndromic PHPT may have mutations of the MEN1 gene or the calcium-sensing receptor (CASR), whose loss of function mutations usually cause FHH1, a disorder associated with mild hypercalcemia and may follow a benign clinical course. Measurement of the urinary calcium-to-creatinine ratio clearance (UCCR) may help to distinguish patients with FHH from those with PHPT, as the majority of FHH patients have low urinary calcium excretion (UCCR < 0.01). Once genetic testing confirms a hereditary cause of PHPT, further genetic testing can be offered to the patients' relatives and subsequent screening can be carried out in these affected family members, which prevents inappropriate testing in normal individuals.

Multiple endocrine neoplasia type 1 (MEN1) is a syndrome characterized by tumors in multiple organs. Although being a dominantly inherited monogenic disease, disease phenotypes are unpredictable and differ even among members of the same family. There is growing evidence for the role of modifier genes in the alteration of the course of this disease. However, genome-wide screening data are still lacking. In our study, we addressed the different outcomes of the disease, focusing on pituitary and adrenocortical tumors. By means of exome sequencing we identified the affected signaling pathways that segregated with those symptoms. Most significantly, we identified damaging alterations in numerous structural genes responsible for cell adhesion and migration. Additionally, in the case of pituitary tumors, genes related to neuronal function, survival, and morphogenesis were repeatedly identified, while in patients with adrenocortical tumors, TLR10, which is involved in the regulation of the innate immunity, was commonly modified. Our data show that using exome screening, it is possible to find signatures which correlate with the given clinical MEN1 outcomes, providing evidence that studies addressing modifier effects in MEN1 are reasonable.

Protein-truncating germline pathogenic variants in the N- and C-terminal exons (2, 9, and 10) of the MEN1 gene may be associated with aggressive pancreatic neuroendocrine tumors. However, the impact of these variants on parathyroid disease is poorly understood. We sought to investigate the effects of genotype and surgical approach on clinical phenotype and postoperative outcomes in patients with multiple endocrine neoplasia type 1 (MEN1)-related primary hyperparathyroidism.

We identified patients with MEN1 evaluated at our institution from 1985 to 2020 and stratified them by genotype, (truncating variants in exons 2, 9, or 10, or other variants), and index surgical approach, (less-than-subtotal parathyroidectomy [

RESULTS

Of the 209 patients we identified, primary hyperparathyroidism was diagnosed in 194 (93%) and at a younger median age in those with truncating exon 2, 9, or 10 variants compared with other variants (27 years vs 31 years; P = .006). Median disease-free survival was significantly worse in patients who underwent

CONCLUSION

The MEN1 genotype may affect the age of onset of primary hyperparathyroidism and the time to recurrence after surgery. Collapse

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MESH Headings

• Humans
• Adult
• Multiple Endocrine Neoplasia Type 1/complications
• Multiple Endocrine Neoplasia Type 1/genetics
• Multiple Endocrine Neoplasia Type 1/surgery
• Hyperparathyroidism, Primary/genetics
• Hyperparathyroidism, Primary/surgery
• Hyperparathyroidism, Primary/epidemiology
• Neoplasm Recurrence, Local/surgery
• Parathyroidectomy/adverse effects
• Hypoparathyroidism/etiology
• Genotype

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Affiliation(s)

Omair A Shariq Department of Surgery, Mayo Clinic, Rochester, MN.
Vitor B Abrantes Department of Surgery, Mayo Clinic, Rochester, MN
Lauren Y Lu Department of Surgery, Mayo Clinic, Rochester, MN
Peter J Tebben Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
Trenton M Foster Department of Surgery, Mayo Clinic, Rochester, MN
Benzon M Dy Department of Surgery, Mayo Clinic, Rochester, MN
Melanie L Lyden Department of Surgery, Mayo Clinic, Rochester, MN
William F Young Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
Travis J McKenzie Department of Surgery, Mayo Clinic, Rochester, MN

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Pancreatic GHRHomas (pGHRHomas) with acromegaly have unique conditions, harboring the existence of multiple endocrine neoplasia type 1 (MEN 1). Moreover, pituitary lesions are affected by both protracted ectopic GHRH and loss of menin function. Of significance is the clarification of clinicopathological aspects of pGHRHomas in patients with or without MEN 1. From 1977-2016, thirty-six patients with pGHRHomas were reported. Twenty-two out of 36 patients (61%) had pGHRHomas with MEN 1 and 14 patients did not. The former had a tendency of male predominance, benign tumor behavior and fewer metastasis rather than the latter. The latter is a single pGHRHoma accompanied by pituitary enlargement with somatotroph hyperplasia (hyperplasia) caused by protracted ectopic GHRH. Nine patients with MEN 1 underwent transsphenoidal surgery (TSS). The hyperplasia associated with various pituitary adenomas (PAs) including three GH-related adenomas was observed in seven subjects (32%). In these patients, the resection of their pGHRHomas was feasible. Furthermore, all patients with acromegaly due to pGHRHomas without MEN 1 had non-TSS, whereas approximately 70% of those with MEN 1 had unnecessary TSS. The association with hyperplasia and various PAs suggested that formation of the three GH-related adenomas may be induced by the foundations of MEN 1 gene mutations. J. Med. Invest. 71 : 1-8, February, 2024.

Multiple endocrine neoplasia type 4 (MEN4) is a rare multiglandular endocrine neoplasia syndrome, associated with a wide tumor spectrum but hallmarked by primary hyperparathyroidism, which represents the most common clinical feature, followed by pituitary (functional and non-functional) adenomas, and neuroendocrine tumors. MEN4 clinically overlaps MEN type 1 (MEN1) but differs from it for milder clinical features and an older patient's age at onset. The underlying mutated gene, CDKN1B, encodes the cell cycle regulator p27, implicated in cellular proliferation, motility and apoptosis. Given the paucity of MEN4 cases described in the literature, possible genotype-phenotype correlations have not been thoroughly assessed, and specific clinical recommendations are lacking. The present review provides an extensive overview of molecular genetics and clinical features of MEN4, with the aim of contributing to delineate peculiar strategies for clinical management, screening and follow-up of the last and least known MEN syndrome.

A literature search was performed through online databases like MEDLINE and Scopus.

MEN4 is much less common that MEN1, tend to present later in life with a more indolent course, although involving the same primary organs as MEN1. As a consequence, MEN4 patients might need specific diagnostic and therapeutic approaches and a different strategy for screening and follow-up. Further studies are needed to assess the real oncological risk of MEN4 carriers, and to establish a standardized screening protocol. Furthermore, a deeper understanding of molecular genetics of MEN4 is needed in order to explore p27 as a novel therapeutic target.

The optimal therapy of duodenopancreatic neuroendocrine neoplasia (dpNEN), which occurs in the context of multiple endocrine neoplasia type 1, is still a major challenge and is controversial. Due to the rarity of the disease, there is a lack of prospective randomised studies, so that most recommendations regarding the surgical indication and procedure are based on retrospective case series. In summary, surgical therapy is indicated for non-functional dpNEN > 2 cm, suspected malignancy and functionally active dpNEN. Enucleation or formal pancreatic resections with or without lymphadenectomy may be considered. The aim of therapy should be to eliminate hormone-associated symptoms and prevent an aggressive metastatic disease. At the same time, pancreatic function and quality of life should be preserved in the mostly young patients by resections that save as much parenchyma as possible.

Recent studies suggest that the clinical characteristics and biological behavior of pituitary tumors (PITs) in patients with multiple endocrine neoplasia type 1 (MEN1) may not be as aggressive as previously reported. Increased imaging of the pituitary as recommended by screening guidelines identifies more tumors, potentially at an earlier stage. However, it is unknown if these tumors have different clinical characteristics in different MEN1 mutations.

To assess characteristics of patients with MEN1 with and without PITs, and compare among different MEN1 mutations.

Data of patients with MEN1 in a tertiary referral center from 2010 to 2023 were retrospectively analyzed.

Forty-two patients with MEN1 were included. Twenty-four patients had PITs, 3 of which were invasive and managed with transsphenoidal surgery. One PIT enlarged during follow-up. Patients with PITs had a higher median age at MEN1 diagnosis than those without PITs. MEN1 mutations were identified in 57.1% of patients, including 5 novel mutations. In patients with PITs, those with MEN1 mutations (mutation+/PIT+ group) had more additional MEN1-associated tumors than those without (mutation-/PIT+ group). The mutation+/PIT+ group had a higher incidence of adrenal tumors and a lower median age at initial manifestation of MEN1 than the mutation-/PIT+ group. The most common neuroendocrine neoplasm was nonfunctional in the mutation+/PIT+ group and insulin-secreting in the mutation-/PIT+ group.

This is the first study comparing characteristics of patients with MEN1 with and without PITs harboring different mutations. Patients without MEN1 mutations tended to have less organ involvement and it might be reasonable for them to receive less intensive follow-up.

Multiple endocrine neoplasia (MEN) syndromes are a group of hereditary cancer syndromes that can predispose children to endocrine neoplasms developing within the head and neck.

To examine the neoplastic manifestations of MEN type 1 (MEN1) and MEN type 2 (MEN2) in the pediatric head and neck.

Single-institution, retrospective review of pediatric MEN between 2005 and 2022.

Fifty-three children were genetically confirmed with MEN (15 MEN1, 34 MEN2A, and 4 MEN2B), while three patients received clinical diagnoses of MEN1. The male to female ratio was essentially equal (1.15:1), and a documented family history of cancer was present in 89% (50/56). After multidisciplinary evaluation, a familial MEN diagnosis was confirmed in 91% (51/56). The mean ages of initial presentation and surgical intervention were 8.9 years (SD 5) and 9.8 years (SD 4.8), respectively. Although patients with MEN2 received surgery earlier than patients with MEN1 (8.7 vs 12.7 years), surgical patients with MEN2 in this cohort were older relative to current American Thyroid Association (ATA) guidelines primarily due to late presentation. Thyroid malignancies were identified in 36% (9/25) of thyroidectomy specimens (21 MEN2A, 4 MEN2B), with medullary thyroid carcinoma (MTC) present in five MEN2A patients and three MEN2B patients (89%), and papillary thyroid carcinoma (PTC) present in one MEN2A patient (11%). Nearly 90% (8/9) of thyroid malignancies were occult, with some occurring earlier than predicted by current guidelines (ATA-MOD and ATA-H). Central neck dissections were performed in 24% (2 MEN1, 2 MEN2A, and 4 MEN2B), with two MEN2B (50%) demonstrating cervical lymph node (LN) metastases. Additional histopathologic findings included C-cell hyperplasia in 57% (12/21) of MEN2A thyroidectomy patients. Of the eight MEN1 parathyroidectomy patients, four demonstrated parathyroid hyperplasia and four presented with parathyroid adenoma.

Nearly 60% required head and neck procedures. While MEN1 guidelines were appropriate for our cohort, we identified patients with MEN2 that developed MTC earlier than expected based on current ATA guidelines, including children in categories considered lower risk. In conjunction with a multidisciplinary approach, pediatric head and neck surgeons should be aware of the potential need for earlier surgical intervention in the pediatric MEN2 population.

Menin is a scaffold protein encoded by the Men1 gene, which interacts with various transcriptional proteins to activate or repress cellular processes and is a key mediator in multiple organs. Both liver-specific and hepatocyte-specific Menin deficiency promotes high-fat diet-induced liver steatosis in mice, as well as insulin resistance and type 2 diabetic phenotype. The potential link between Menin and hepatic metabolism homeostasis may provide new insights into the mechanism of fatty liver disease.

Disturbance of hepatic Menin expression impacts metabolic pathways associated with non-alcoholic fatty liver disease (NAFLD), including the FoxO signaling pathway, which is similar to that observed in both oleic acid-induced fatty hepatocytes model and biopsied fatty liver tissues, but with elevated hepatic Menin expression and inhibited FABP1. Higher levels of Menin facilitate glucose uptake while restraining fatty acid uptake. Menin targets the expression of FABP3/4/5 and also CD36 or GK, PCK by binding to their promoter regions, while recruiting and deploying the cellular localization of PPARγ and SIRT1 in the nucleus and cytoplasm. Accordingly, Menin binds to PPARγ and/or FoxO1 in hepatocytes, and orchestrates hepatic glucose and fatty acid uptake by recruiting SIRT1.

Menin plays an orchestration role as a transcriptional activator and/or repressor to target downstream gene expression levels involved in hepatic energy uptake by interacting with the cellular energy sensor SIRT1, PPARγ, and/or FoxO1 and deploying their translocations between the cytoplasm and nucleus, thereby maintaining metabolic homeostasis. These findings provide more evidence suggesting Menin could be targeted for the treatment of hepatic steatosis, NAFLD or metabolic dysfunction-associated fatty liver disease (MAFLD), and even other hepatic diseases.

The aim of this study is to evaluate the predictive role of specific clinical factors for the diagnosis of Multiple Endocrine Neoplasia type-1 (MEN1) and type-4 (MEN4) in patients with an initial diagnosis of gastrointestinal, bronchial, or thymic neuroendocrine tumor (NET).

Patients referred to the NET Unit between June 2021 and December 2022 with a diagnosis of NET and at least one clinical criterion of suspicion for MEN1 and MEN4 underwent molecular analysis of the MEN1 and CDKN1B genes. Phenotypic criteria were: (1) age ≤ 40 years; (2) NET multifocality; (3) MEN1/4-associated manifestations other than NETs; and (4) endocrine syndrome related to NETs or pituitary/adrenal tumors.

A total of 22 patients were studied. In 18 patients (81.8%), the first-level genetic test was negative (Group A), while four patients (25%) were positive for MEN1 (Group B). No patient was positive for MEN4. In Group A, 10 cases had only one clinical criterion, and three patients met three criteria. In Group B, three patients had three criteria, and one met all criteria.

These preliminary data show that a diagnosis of NET in patients with a negative family history is suggestive of MEN1 in the presence of ≥three positive phenotypic criteria, including early age, multifocality, multiple MEN-associated manifestations, and endocrine syndromes. This indication may allow optimization of the diagnosis of MEN in patients with NET.

Primary hyperparathyroidism (PHPT) includes sporadic PHPT and hereditary PHPT. However, until now, there have been no exact data on the proportion and composition of hereditary PHPT in the Chinese PHPT population. This study aimed to clarify the proportion and composition of hereditary PHPT in patients at a large academic center in Beijing, China, and to analyze genotype-phenotype characteristics. A total of 394 newly diagnosed Han PHPT patients who consented to genetic screening were enrolled. Targeted next-generation sequencing (T-NGS) (including for MEN1, RET, CDKN1B, CaSR, HRPT2/CDC73, GNA11, AP2S1, GCM2), combined with MEN1-multiplex ligation-dependent probe amplification (MLPA) and CDC73-MLPA, was used for genetic screening. Diagnosis of hereditary PHPT was based on clinical manifestations, family history, and genetic screening. Thirty-seven pathogenic (P)/likely pathogenic (LP) variants were detected in 41 patients via T-NGS, and three patients carried long-range deletions of MEN1 or CDC73 detected by MLPA, with a variant detection rate of 11.2% (44/394). In total, 30 patients were clinically diagnosed with MEN1. Combined with genetic and clinical screening, the rate of hereditary PHPT in this study was 18.8% (74/394). For purposes of comparison, the rate of unequivocal nonhereditary PHPT was 66.5% (262/394); 14.7% (58/394) did not exhibit the clinical features of hereditary PHPT but carried variants of uncertain clinical significance and so could not be clearly categorized. Both the age at hospital visit (43.6 ± 14.0 versus 53.7 ± 14.9 years) and age at onset (35.4 ± 13.8 versus 50.6 ± 14.8 years) in the hereditary group (n = 74) were significantly lower than those in the nonhereditary group (n = 262). Higher levels of ionized calcium and serum β-CTX were observed in the hereditary group; proportions of parathyroid hyperplasia and multigland involvement were also higher. In addition to multigland disease and positive family history, it is recommended that patients with an age of onset less than 38 should be screened for hereditary forms. © 2023 American Society for Bone and Mineral Research (ASBMR).

A clinical diagnosis of multiple endocrine neoplasia type 1 (MEN1) syndrome is usually confirmed with genetic testing in the germline. It is expected that menin protein expression is lost in MEN1-related tumors. Therefore, we investigated the potential of menin immunohistochemistry in parathyroid adenomas as an additional tool in the recognition and genetic diagnosis of MEN1 syndrome. Local pathology archives were searched for parathyroid tumors from patients with MEN1 syndrome and without MEN1, including sporadic, patients with multiple endocrine neoplasia type 2A and hyperparathyroidism-jaw parathyroid tumors. Menin immunohistochemistry was performed and its use to identify MEN1-related tumors was assessed. Twenty-nine parathyroid tumors from 16 patients with MEN1 and 61 patients with parathyroid tumors from 32 non-MEN1 were evaluated. Immunohistochemical nuclear menin loss in one or more tumors was found in 100% of patients with MEN1 and 9% of patients with non-MEN1. In patients with multiple tumors, menin loss in at least one tumor was seen in 100% of 8 patients with MEN1 and 21% of patients with 14 non-MEN1. Using a cutoff of at least 2 tumors showing menin loss per patient, the positive and negative predictive values for the diagnosis MEN1 were both 100%. The practical and additional value of menin immunohistochemistry in clinical genetic MEN1 diagnosis is further illustrated by menin immunohistochemistry in 2 cases with a germline variant of unknown significance in the MEN1 gene. Menin immunohistochemistry is useful in the recognition of MEN1 syndrome as well as in the clinical genetic analysis of patients with inconclusive MEN1 germline testing.

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary endocrine tumor syndrome caused by pathogenic variants in the MEN1 gene, and most patients with this syndrome initially develop primary hyperparathyroidism (PHPT). Here, we report the case of a family wherein a germline MEN1 variant was detected and multiple pancreatic neuroendocrine tumors (PanNETs) were observed at the initial evaluation. A 40-year-old woman presented with a complaint of abdominal discomfort, and a close examination revealed multiple pancreatic tumors. Distal pancreatectomy with splenectomy was performed, and the diagnosis was nonfunctional PanNETs. Five years later, her 76-year-old mother was referred to the hospital with multiple pancreatic tumors. A genetic test revealed that both patients harbored a previously unreported germline variant in the MEN1 gene. Although it was classified as a variant of uncertain significance, we suspect that it may be associated with the pathogenesis of these lesions. This case report presents a new disease concept-familial isolated pancreatic neuroendocrine tumors, or FIPNETs-in patients harboring a pathogenic variant in the MEN1 gene who experience only pancreatic lesions. We suggest that clinicians consider genetic testing for the MEN1 gene in patients with multiple pancreatic lesions who show no signs of PHPT.

Hereditary cancer syndromes account for nearly 10% of cancers even though they are often underdiagnosed. Finding a pathogenic gene variant could have dramatic implications in terms of pharmacologic treatments, tailored preventive programs, and familiar cascade testing. However, diagnosing a hereditary cancer syndrome could be challenging because of a lack of validated testing criteria or because of their suboptimal performance. In addition, many clinicians are not sufficiently well trained to identify and select patients that could benefit from a genetic test. Herein, we searched the available literature to comprehensively review and categorize hereditary cancer syndromes affecting adults with the aim of helping clinicians in their daily clinical practice through a visual tool.

CDKN1B mutations were established as a cause of multiple endocrine neoplasia 4 (MEN4) syndrome in patients with MEN1 phenotype without a mutation in the MEN1 gene. In addition, variants in other cyclin-dependent kinase inhibitors (CDKIs) were found in some MEN1-like cases without the MEN1 mutation. We aimed to describe novel germline mutations of these genes in patients with primary hyperparathyroidism (PHPT).

During genetic screening for familial hyperparathyroidism, three novel CDKIs germline mutations in three unrelated cases between January 2019 and November 2021 were identified. In this report, we describe clinical features, DNA sequence analysis, and familial segregation studies based on these patients and their relatives. Genome-wide DNA study of loss of heterozygosity (LOH), copy number variation (CNV), and p27/kip immunohistochemistry was performed on tumour samples.

DNA screening was performed for atypical parathyroid adenomas in cases 1 and 2 and for cystic parathyroid adenoma and young age at diagnosis of PHPT in case 3. Genetic analysis identified likely pathogenic variants of CDKN1B in cases 1 and 2 and a variant of the uncertain significance of CDKN2C, with uniparental disomy in the tumour sample, in case 3. Neoplasm screening of probands showed other non-endocrine tumours in case 1 (colon adenoma with dysplasia and atypical lipomas) and case 2 (aberrant T-cell population) and a non-functional pituitary adenoma in case 3.

Germline mutations in CDKIs should be included in gene panels for genetic testing of primary hyperparathyroidism. New germline variants here described can be added to the current knowledge.

Multiple endocrine neoplasia type 1 syndrome (MEN1) is a disease caused by mutations in the MEN1 tumor suppressor gene leading to hyperparathyroidism, pituitary adenomas, and entero-pancreatic neuroendocrine tumors. Pancreatic neuroendocrine tumors (PNETs) are a major cause of mortality in patients with MEN1. Identification of consistent genotype-phenotype correlations has remained elusive, but MEN1 mutations in exons 2, 9, and 10 may be associated with metastatic PNETs; patients with these mutations may benefit from more intensive surveillance and aggressive treatment. In addition, epigenetic differences between MEN1-associated PNETs and sporadic PNETs are beginning to emerge, but further investigation is required to establish clear phenotypic associations.

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant disorder without a good genotype-phenotype correlation, characterized by tumor predisposition in the parathyroid gland, anterior pituitary, and pancreatic islet cells. Here, we describe a 37-year-old male with previous history of nephrolithiasis, with a 1-year history of recurrent hypoglycemic episodes. Physical examination revealed the presence of two lipomas. Family history revealed primary hyperparathyroidism (PHPT), hyperprolactinemia, and multiple non-functioning pancreatic neuroendocrine tumors. Initial laboratories revealed hypoglycemia and primary hyperparathyroidism. A fasting test was positive after 3 hours of initiation. An abdominal CT Scan demonstrated a 28 × 27 mm mass in the pancreatic tail and bilateral nephrolithiasis. A distal pancreatectomy was done. After surgery, the patient persisted with hypoglycemic episodes that were managed with diazoxide and frequent feedings. A parathyroid Tc-99 m MIBI scan with SPECT/CT imaging demonstrated two hot uptake lesions compatible with abnormally functioning parathyroid tissue. Surgical treatment was offered; however, the patient decided to postpone the procedure. Direct sequence analysis of MEN1 gene revealed heterozygosity for a pathogenic insertion c.1224_1225insGTCC (p.Cys409Valfs*41). DNA sequence analysis was done to six of his first-degree relatives. A sister with clinical diagnosis of MEN1 and a pre-symptomatic brother were positive for the same MEN1 variant. To our knowledge, this is the first report of a genetically confirmed case of MEN1 in our country and is the first report in literature of the c.1224_1225insGTCC variant related to a clinically affected family.

Hereditary pituitary tumorigenesis is seen in a relatively small proportion (around 5%) of patients with pituitary neuroendocrine tumors (PitNETs). The aim of the current review is to describe the main clinical and molecular features of such pituitary tumors associated with hereditary or familial characteristics, many of which have now been genetically identified. The genetic patterns of inheritance are classified into isolated familial PitNETs and the syndromic tumors. In general, the established genetic causes of familial tumorigenesis tend to present at a younger age, often pursue a more aggressive course, and are more frequently associated with growth hormone hypersecretion compared to sporadic tumors. The mostly studied molecular pathways implicated are the protein kinase A and phosphatidyl-inositol pathways, which are in the main related to mutations in the syndromes of familial isolated pituitary adenoma (FIPA), Carney complex syndrome, and X-linked acrogigantism. Another well-documented mechanism consists of the regulation of p27 or p21 proteins, with further acceleration of the pituitary cell cycle through the check points G1/S and M/G1, mostly documented in multiple endocrine neoplasia type 4. In conclusion, PitNETs may occur in relation to well-established familial germline mutations which may determine the clinical phenotype and the response to treatment, and may require family screening.

Chromatin-binding proteins are critical regulators of cell state in haematopoiesis1,2. Acute leukaemias driven by rearrangement of the mixed lineage leukaemia 1 gene (KMT2Ar) or mutation of the nucleophosmin gene (NPM1) require the chromatin adapter protein menin, encoded by the MEN1 gene, to sustain aberrant leukaemogenic gene expression programs3-5. In a phase 1 first-in-human clinical trial, the menin inhibitor revumenib, which is designed to disrupt the menin-MLL1 interaction, induced clinical responses in patients with leukaemia with KMT2Ar or mutated NPM1 (ref. 6). Here we identified somatic mutations in MEN1 at the revumenib-menin interface in patients with acquired resistance to menin inhibition. Consistent with the genetic data in patients, inhibitor-menin interface mutations represent a conserved mechanism of therapeutic resistance in xenograft models and in an unbiased base-editor screen. These mutants attenuate drug-target binding by generating structural perturbations that impact small-molecule binding but not the interaction with the natural ligand MLL1, and prevent inhibitor-induced eviction of menin and MLL1 from chromatin. To our knowledge, this study is the first to demonstrate that a chromatin-targeting therapeutic drug exerts sufficient selection pressure in patients to drive the evolution of escape mutants that lead to sustained chromatin occupancy, suggesting a common mechanism of therapeutic resistance.