Management impact: effects on quality of life and prognosis in MEN1

Safety and Efficacy of Peptide Receptor Radionuclide Therapy in Multiple Endocrine Neoplasia Syndrome: A Single-center Experience

PURPOSE

Peptide receptor radionuclide therapy (PRRT) is recommended and approved in advanced neuroendocrine tumors (NETs). There is a lack of data on the utility of PRRT in multiple endocrine neoplasia (MEN) syndrome. This study explores the utility of PRRT in MEN syndrome patients with inoperable/metastatic NETs.

METHODS

A single-center retrospective analysis of MEN syndrome patients with advanced NETs referred for PRRT was done. Upto 4 cycles of 177Lu-DOTATATE (5.5-7.4 GBq/cycle) were administered every 8-12 weeks. Treatment-related adverse events were assessed using CTCAE v5. The best response to PRRT was evaluated using RECIST 1.1. Follow-up was done to calculate the progression-free survival (PFS) and overall survival (OS).

RESULTS

The data of 15 patients with a median age of 36 years (IQR: 32-49) was analyzed. Fourteen patients had MEN-1 syndrome, and 1 had MEN-2 syndrome. Thirteen patients with MEN-1 syndrome had gastroenteropancreatic (GEP) NET, with the multifocal primary as the most common finding (n=7). One patient had thymic carcinoid. All patients had hyperparathyroidism, while 6 had pituitary adenoma. Fifty-three cycles of 177Lu-DOTATATE (range: 1-4) were administered with a median cumulative activity of 27.8 GBq. Twelve patients (80%) showed grade 1/2 adverse events, with leukopenia being the most common. Six patients achieved partial response (43% ORR), 6 showed stable disease (86% DCR), 2 (14%) showed disease progression during PRRT, while 1 patient was lost to follow-up. The median PFS was 32.6 months (95% CI: 14.7-not reached) with an estimated 1- and 5-year PFS rate of 86.2% (95% CI: 68-100) and 46.3% (95% CI: 13-80), and estimated 5-year OS rate of 76.2% (95% CI: 52.1-100).

CONCLUSION

177Lu-DOTATATE is a safe and effective treatment option for advanced NETs in MEN syndrome. However, large-sized multicentric prospective studies are required.

An Updated Perspective of the Clinical Features and Parathyroidectomy Impact in Primary Hyperparathyroidism Amid Multiple Endocrine Neoplasia Type 1 (MEN1): Focus on Bone Health

Background: Multiple endocrine neoplasia type 1 (MEN1)-related primary hyperparathyroidism (MPHPT) belongs to genetic PHPT that accounts for 10% of all PHPT cases, being considered the most frequent hereditary PHPT (less than 5% of all PHPT). Objective: We aimed to provide an updated clinical perspective with a double purpose: to highlight the clinical features in MPHPT, particularly, the bone health assessment, as well as the parathyroidectomy (PTx) impact. Methods: A comprehensive review of the latest 5-year, English-published, PubMed-accessed original studies. Results: The sample-based analysis (n = 17 studies) enrolled 2426 subjects (1720 with MPHPT). The study design was retrospective, except for one prospective and one case-control study. The maximum number of patients per study was of 517. Female predominance (an overall female-to-male ratio of 1.139) was confirmed (except for three studies). Age at MPHPT diagnosis (mean/median per study): 28.7 to 43.1 years; age at PTx: 32 to 43.5 years. Asymptomatic PHPT was reported in 38.3% to 67% of MPHPT. Mean total calcium varied between 1.31 and 2.88 mmol/L and highest PTH was of 317.2 pg/mL. Two studies reported similar PTH and calcaemic levels in MPHPT vs. sporadic PHPT, while another found higher values in MPHPT. Symptomatic vs. asymptomatic patients with MPHPT had similar PTH and serum calcium levels (n = 1). Osteoporosis (n = 8, N = 723 with MPHPT) was reported in 10% to 55.5% of cases, osteopenia in 5.88% to 43.9% (per study); overall fracture rate was 10% (of note, one study showed 0%). Lower bone mineral density (BMD) at DXA (n = 4) in MPHPT vs. sporadic PHPT/controls was found by some studies (n = 3, and only a single study provided third distal radius DXA-BMD assessment), but not all (n = 1). Post-PTx DXA (n = 3, N = 190 with MPHPT) showed a BMD increase (e.g., +8.5% for lumbar spine, +2.1% for total hip, +4.3% for femoral neck BMD); however, post-operatory, BMD remains lower than controls. Trabecular bone score (TBS) analysis (n = 2, N = 142 with MPHPT vs. 397 with sporadic PHPT) showed a higher prevalence of reduced TBS (n = 1) or similar (n = 1). PTx analysis in MPHPT (n = 14): rate of subtotal PTx of 39% to 66.7% (per study) or less than subtotal PTx of 46.9% (n = 1). Post-PTx complications: persistent PHPT (5.6% to 25%), recurrent PHPT (16.87% to 30%, with the highest re-operation rate of 71% in one cohort); hypoparathyroidism (12.4% to 41.7%). Genetic analysis pointed out a higher risk of post-PTx recurrence in exon 10 MEN1 pathogenic variant. Post-PTx histological exam showed a multi-glandular disease in 40% to 52.1% of MPHPT, and a parathyroid carcinoma prevalence of 1%. Conclusions: MPHPT remains a challenging ailment amid a multi-layered genetic syndrome. Current data showed a lower age at MPHPT diagnosis and surgery than found in general population, and a rate of female predominance that is lower than seen in sporadic PHPT cases, but higher than known, for instance, in MEN2. The bone involvement showed heterogeneous results, more consistent for a lower BMD, but not necessarily for a lower TBS vs. controls. PTx involves a rather high rate of recurrence, persistence and redo surgery. About one out of ten patients with MPHPT might have a prevalent fracture and PTx improves the overall bone health, but seems not to restore it to the general population level, despite the young age of the subjects. This suggests that non-parathyroid components and potentially menin protein displays negative bone effects in MEN1.

Importance of early detection in multiple endocrine neoplasia type 1: Clinical insights and future directions

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal-inherited syndrome involving multiple endocrine tumors. It is characterized by multiple mutations in the tumor suppressor gene MEN1, which is located on chromosome 11q13. As main etiology of MEN1 is genetic mutations, clinical symptoms may vary. In this editorial, we comment on the article by Yuan et al. This article describes a case of (MEN1) characterized by low incidence and diagnostic complexity. MEN1 commonly presents as parathyroid, pancreatic, and pituitary tumors. Diagnosis requires a combination of serologic tests, magnetic resonance imaging, computed tomography, endoscopic ultrasonography, immunologic and pathology. The diagnosis is unique depending on the site of disease. Surgical resection is the treatment of choice for MEN1. The prognosis depends on the site of origin, but early detection and intervention is the most effective.

Adolescent primary hyperparathyroidism

Adolescent primary hyperparathyroidism (PHPT) is a rare endocrine disorder bearing distinctions from the adult form. This review examines its unique aspects, focusing on clinical presentation, genetic etiologies, genotype-phenotype correlations, and therapeutic management. Adolescent PHPT often has a genetic basis, whether familial, syndromic, or apparently sporadic, and identifying the underlying genetic cause is important for patient care. The clinical presentation is predominantly symptomatic worldwide. Unique manifestations in this age group include rickets, short stature, and slipped capital femoral epiphysis. Genotype-specific differences are evident in the adolescent PHPT characteristics. Diagnostic evaluation requires careful interpretation of biochemical and dual-energy X-ray absorptiometry findings using age and gender-specific reference ranges, with targeted screening for syndrome-associated neoplasms. Surgery remains the cornerstone of management. Current knowledge gaps in their management include treatment protocols for multiple endocrine neoplasia type 1-associated PHPT, the efficacy and safety of nonsurgical options, and long-term post-surgical outcomes.

The polar vessel sign: insights from CT imaging analysis in Asian Indian primary hyperparathyroidism

PURPOSE

Data on the polar vessel sign (enlarged feeding vessel terminating in parathyroid lesions) on four-dimensional computed tomography (4D-CT) is limited. We performed a retrospective analysis to determine the prevalence, predictors, and adjunctive utility of polar vessel sign in pre-operative 4D-CT of patients with primary hyperparathyroidism (PHPT).

METHODS

One radiologist blinded to the patients' details reported the 4D-CT of eighty-four operated patients with histopathology-proven single-gland PHPT. Two protocols were used to obtain arterial-phase images: timed via bolus tracking (n = 41) or fixed at 20 s after contrast injection (n = 43).

RESULTS

Seventy-one patients were symptomatic for PHPT, with median serum calcium 12.1 mg/dL. On the arterial phase of 4D-CT, 88.1% of lesions had the polar vessel sign, including 7/9 asymptomatic patients, 6/6 parathyroid carcinomas, and 3/4 ectopic(1:mediastinum, 2:thyro-thymic ligament). Predictors of polar vessel sign were maximum lesion dimension (2.2 vs. 1.4 cm; P = 0.03), solid-cystic CT morphology (47.3% vs. none; P = 0.004), and bolus tracking-timed arterial phase (55.4% vs. none; P = 0.001). Of these, bolus tracking improved the polar vessel's visualization (100% vs. 76.7%; P = 0.001) independent of lesion dimension and solid-cystic morphology. The latter two predicted polar vessel sign in images obtained at a fixed interval (20 s). A significantly lower proportion of bolus tracking-timed scans had lesion percentage arterial enhancement (PAE) < 128.9% (2/41 vs. 9/43; P = 0.04). Even with suboptimal PAE, the polar vessel helped identify 9/11 lesions.

CONCLUSION

The polar vessel sign demonstrated an additive role to PAE during CT reporting. Bolus tracking is valuable in optimizing vessel and tumor arterial enhancement and is easily incorporated into parathyroid 4D-CT protocol.

Improving early diagnosis of multiple endocrine neoplasia type 1 by assessing the gastrointestinal symptoms, hypercalcemia, and elevated serum gastrin

Despite advancements in the field, early diagnosis of multiple endocrine neoplasia type 1 (MEN1) remains unachievable. This letter to the editor highlighted the importance of carefully assessing gastrointestinal symptoms, hypercalcemia, and elevated serum gastrin levels, as suggested by Yuan et al in their paper. They focused on a patient with recurrent abdominal pain and diarrhea whose diagnostic path led to establishing a MEN1 diagnosis within a year. This emphasized the need for clinicians to consider MEN1 in patients with similar presentations, particularly when gastrointestinal symptoms persist or recur after discontinuation of proton pump inhibitors, especially knowing that early recognition and intervention are crucial for improving patient outcomes.

Multiple Endocrine Neoplasia Type 1

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is a rare genetic disease of autosomal dominant inheritance, with an estimated prevalence of 3-20/100 000. Its main feature is neuroendocrine neoplasia in the parathyroid glands, the endocrine pancreas, the duodenum, and the pituitary gland. In this article, we review the diagnostic and therapeutic options for MEN1-associated tumors.

METHODS

We present an analysis and evaluation of retrospective case studies retrieved from PubMed, guidelines from Germany and abroad, and our own experience.

RESULTS

The disease is caused by mutations in the MEN1 gene. Mutation carriers should participate in a regular, specialized screening program from their twenties onward. The early diagnosis and individualized treatment of MEN1-associated tumors can prevent the development of life-threatening hormonal syndromes and prolong the expected life span of MEN1 patients from 55 to 70 years, as well as improving their quality of life. Surgical treatment is based on the location, size, growth dynamics, and functional activity of the tumors. The evidence for treatment strategies is derived from retrospective studies only (level III evidence) and the optimal treatment is often a matter of debate. This is a further reason for treatment in specialized centers.

CONCLUSION

MEN1 is a rare disease, and, consequently, the evidence base for its treatment is limited. Carriers of disease-causing mutations in the MEN1 gene should be cared for in specialized interdisciplinary centers, so that any appreciable tumor growth or hormonal activity can be detected early and organ-sparing treatment can be provided.

Major Genetic Motifs in Pituitary Adenomas: A Practical Literature Update

BACKGROUND

The literature includes many studies examining the genetic abnormalities that influence pituitary adenomas (PAs). We aimed to state the collective knowledge on the genetic underpinnings of PAs by organizing, summarizing, and consolidating the literature to serve as a comprehensive review for scientists and clinicians of the most up-to-date information underlying the genetic landscape of PAs.

METHODS

The PubMed and Google Scholar databases were searched using multiple key words and combined Medical Subject Headings terms; only articles published in English between January 2000 and January 2022 were included. Articles in which the focus did not relate to genetics, that included mainly anecdotal evidence, or that were single case studies were eliminated.

RESULTS

PAs are one of the most common intracranial neoplasms. However, the genetic underpinnings for these tumors are not yet fully elucidated. There are several categories of PAs: clinically significant versus not clinically significant, functional versus nonfunctional, and germline-derived versus sporadic origin. Each of these disease subcategories is characterized by unique genetic aberrations. Recently, more genes and other types of genetic aberrations have been identified as possible causes of PAs, such as copy number variations and altered levels of microRNAs.

CONCLUSIONS

This review serves to consolidate and summarize the literature discussing the genetic motifs of PAs to help physicians and scientists deliver patient-centered therapies.

Approach of Multiple Endocrine Neoplasia Type 1 (MEN1) Syndrome-Related Skin Tumors

Non-endocrine findings in patients with MEN1 (multiple endocrine neoplasia) syndrome also include skin lesions, especially tumor-type lesions. This is a narrative review of the English-language medical literature including original studies concerning MEN1 and dermatological issues (apart from dermatologic features of each endocrine tumor/neuroendocrine neoplasia), identified through a PubMed-based search (based on clinical relevance, with no timeline restriction or concern regarding the level of statistical significance). We identified 27 original studies involving clinical presentation of patients with MEN1 and cutaneous tumors; eight other original studies that also included the genetic background; and four additional original studies were included. The largest cohorts were from studies in Italy (N = 145 individuals), Spain (N = 90), the United States (N = 48 and N = 32), and Japan (N = 28). The age of patients varied from 18 to 76 years, with the majority of individuals in their forties. The most common cutaneous tumors are angiofibromas (AF), collagenomas (CG), and lipomas (L). Other lesions are atypical nevi, basocellular carcinoma, squamous cell carcinoma, acrochordons, papillomatosis confluens et reticularis, gingival papules, and cutaneous T-cell lymphoma of the eyelid. Non-tumor aspects are confetti-like hypopigmentation, café-au-lait macules, and gingival papules. MEN1 gene, respective menin involvement has also been found in melanomas, but the association with MEN1 remains debatable. Typically, cutaneous tumors (AF, CG, and L) are benign and are surgically treated only for cosmetic reasons. Some of them are reported as first presentation. Even though skin lesions are not pathognomonic, recognizing them plays an important role in early identification of MEN1 patients. Whether a subgroup of MEN1 subjects is prone to developing these types of cutaneous lesions and how they influence MEN1 evolution is still an open issue.

Comparison of 68Ga-DOTA-NaI3-Octreotide/tyr3-octreotate positron emission tomography/computed tomography and contrast-enhanced computed tomography in localization of tumors in multiple endocrine neoplasia 1 syndrome

The optimum imaging modality for the screening of multiple endocrine neoplasia type 1 (MEN1)-associated tumors is not well established. Here, we compare the performance of contrast-enhanced CT (CECT) versus ⁶⁸Ga DOTA-NOC/TATE PET/CT in MEN1 patients. The retrospective case record study is conducted at a tertiary health-care center. Thirty-four patients, who have undergone both CECT and ⁶⁸Ga DOTA-NOC/ TATE PET, were included in the analysis. CECT had higher per-lesion sensitivity than ⁶⁸Ga DOTA-NOC/TATE PET/CT for the detection of parathyroid lesions, (82.6% vs. 24.6%, P < 0.001). ⁶⁸Ga DOTA-NOC/TATE PET/CT had higher per-lesion sensitivity than CECT for the detection of metastases (85% vs. 47.5%, P < 0.001) and gastrinomas (90% vs. 10%, P = 0.003). When combined use of the two imaging modalities is compared to CECT alone (63.7% vs. 93.1%, P = 0.00012) and ⁶⁸Ga-DOTA-NOC/TATE PET/CT alone (74.1% vs. 93.1%, P = 0.0057), it provided significantly higher per-lesion sensitivity for the detection of gastroenteropancreatic neuroendocrine tumors (GEP-NETs). ⁶⁸Ga-DOTA-NOC/ TATE PET was more sensitive for the detection of gastrinomas and metastases than CECT, whereas it was less sensitive for the detection of parathyroid lesions than CECT. The combined use of both the imaging modalities significantly increases the sensitivity for detection of GEP-NETs.

Two well-differentiated pancreatic neuroendocrine tumor mouse models

Multiple endocrine neoplasia type 1 (MEN1) is a genetic syndrome in which patients develop neuroendocrine tumors (NETs), including pancreatic neuroendocrine tumors (PanNETs). The prolonged latency of tumor development in MEN1 patients suggests a likelihood that other mutations cooperate with Men1 to induce PanNETs. We propose that Pten loss combined with Men1 loss accelerates tumorigenesis. To test this, we developed two genetically engineered mouse models (GEMMs)-MPR (Men1flox/flox Ptenflox/flox RIP-Cre) and MPM (Men1flox/flox Ptenflox/flox MIP-Cre) using the Cre-LoxP system with insulin-specific biallelic inactivation of Men1 and Pten. Cre in the MPR mouse model was driven by the transgenic rat insulin 2 promoter while in the MPM mouse model was driven by the knock-in mouse insulin 1 promoter. Both mouse models developed well-differentiated (WD) G1/G2 PanNETs at a much shorter latency than Men1 or Pten single deletion alone and exhibited histopathology of human MEN1-like tumor. The MPR model, additionally, developed pituitary neuroendocrine tumors (PitNETs) in the same mouse at a much shorter latency than Men1 or Pten single deletion alone as well. Our data also demonstrate that Pten plays a role in NE tumorigenesis in pancreas and pituitary. Treatment with the mTOR inhibitor rapamycin delayed the growth of PanNETs in both MPR and MPM mice, as well as the growth of PitNETs, resulting in prolonged survival in MPR mice. Our MPR and MPM mouse models are the first to underscore the cooperative roles of Men1 and Pten in cancer, particularly neuroendocrine cancer. The early onset of WD PanNETs mimicking the human counterpart in MPR and MPM mice at 7 weeks provides an effective platform for evaluating therapeutic opportunities for NETs through targeting the MENIN-mediated and PI3K/AKT/mTOR signaling pathways.

Paediatric and young adult manifestations and outcomes of multiple endocrine neoplasia type 1

CONTEXT

Multiple endocrine neoplasia 1 (MEN 1) is an autosomal dominant disease presenting as hyperplasia and neoplasia of parathyroid, pituitary and enteropancreatic tissues. Over 90% of gene carriers develop phenotypic disease by age 30 years, potentially with onset of asymptomatic disease during childhood and adolescence.

OBJECTIVE

To describe the paediatric and young adult manifestations of MEN 1.

DESIGN

Descriptive retrospective study of 180 patients with a common MEN1 genotype. The paediatric and young adult (age <22 years) manifestations were determined using hospital records and disease surveillance data.

RESULTS

Primary hyperparathyroidism (PHPT) was identified in 42 patients (mean age 17.2 ± 3.3 years). Parathyroidectomy was performed in 16 (38.1%; mean age 17.8 ± 3.2). Four patients experienced recurrent PHPT (25%), and six (37.5%) developed permanent hypoparathyroidism. Pituitary disease was identified in 13 patients. Prolactinoma was found in nine patients (mean age 16.6 ± 2.6 years) of whom four (44.4%) had macroprolactinoma. Two patients required surgical intervention; dopamine agonists showed efficacy in six patients. Two patients with Cushing's disease were successfully treated surgically. Three patients with nonfunctioning pituitary microadenoma managed conservatively. Pancreatic neuroendocrine neoplasms (pNENs) were diagnosed in 12 patients (mean age 17.0 ± 2.6 years): three patients with insulinoma successfully resected (two resected and one exhibiting perineural invasion) and nine patients with nonfunctioning adenomas (NFAs).

CONCLUSION

Pituitary adenomas, PHPT and pNENs are encountered in the paediatric and young adult MEN 1 population. Successful outcomes are typically achieved using standard medical and surgical paradigms; however, parathyroidectomy was associated with a substantial complication rate.

A novel case of myxoid variant of adrenocortical carcinoma in a patient with multiple endocrine neoplasia type 1

Adrenocortical carcinoma (ACC) is a rare malignancy arising from adrenocortical parenchymal cells. Myxoid ACC is one of the newly identified, rare, but important histological variants of ACC, characterized by the presence of abundant extracellular Alcian Blue-positive myxoid material. Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant cancer predisposition syndrome, and the incidence of ACC in MEN1 patients has been reported to be between 1.4% and 6%. Here, we report the case of a 68-year-old Japanese woman harboring the past history of MEN1 associated with insulinoma, pituitary tumor, and hyperparathyroidism. She presented to our hospital with hypertension and hypokalemia. Imaging studies revealed a right adrenal tumor, and histological examination revealed myxoid ACC. Despite surgical resection of the tumor and mitotane therapy, the patient died 6 months after the surgery. To the best of our knowledge, this is the first reported case of the myxoid variant of ACC in a patient with MEN1. The patient's clinical course was characterized by the development of both multiple endocrine and non-endocrine neoplasm, hyperaldosteronism, and aggressive biological behavior. This case confirmed that myxoid morphology was also associated with aggressive behavior in ACC, but further studies are required to clarify the association between MEN1 and myxoid ACC.

Multiple Endocrine Neoplasia Type 1 (MEN1): An Update and the Significance of Early Genetic and Clinical Diagnosis

Multiple endocrine neoplasia type 1 (MEN1) is a rare hereditary tumor syndrome inherited in an autosomal dominant manner and characterized by a predisposition to a multitude of endocrine neoplasms primarily of parathyroid, enteropancreatic, and anterior pituitary origin, as well as nonendocrine neoplasms. Other endocrine tumors in MEN1 include foregut carcinoid tumors, adrenocortical tumors, and rarely pheochromocytoma. Nonendocrine manifestations include meningiomas and ependymomas, lipomas, angiofibromas, collagenomas, and leiomyomas. MEN1 is caused by inactivating mutations of the tumor suppressor gene MEN1 which encodes the protein menin. This syndrome can affect all age groups, with 17% of patients developing MEN1-associated tumors before 21 years of age. Despite advances in the diagnosis and treatment of MEN1-associated tumors, patients with MEN1 continue to have decreased life expectancy primarily due to malignant neuroendocrine tumors. The most recent clinical practice guidelines for MEN1, published in 2012, highlight the need for early genetic and clinical diagnosis of MEN1 and recommend an intensive surveillance approach for both patients with this syndrome and asymptomatic carriers starting at the age of 5 years with the goal of timely detection and management of MEN1-associated neoplasms and ultimately decreased disease-specific morbidity and mortality. Unfortunately, there is no clear genotype-phenotype correlation and individual mutation-dependent surveillance is not possible currently.

Germline mutation landscape of multiple endocrine neoplasia type 1 using full gene next-generation sequencing

Background Loss-of-function germline MEN1 gene mutations account for 75-95% of patients with multiple endocrine neoplasia type 1 (MEN1). It has been postulated that mutations in non-coding regions of MEN1 might occur in some of the remaining patients; however, this hypothesis has not yet been fully investigated. Objective To sequence for the entire MEN1 including promoter, exons and introns in a large MEN1 cohort and determine the mutation profile. Methods and patients A target next-generation sequencing (tNGS) assay comprising 7.2 kb of the full MEN1 was developed to investigate germline mutations in 76 unrelated MEN1 probands (49 familial, 27 sporadic). tNGS results were validated by Sanger sequencing (SS), and multiplex ligation-dependent probe amplification (MLPA) assay was applied when no mutations were identifiable by both tNGS and SS. Results Germline MEN1 variants were verified in coding region and splicing sites of 57/76 patients (74%) by both tNGS and SS (100% reproducibility). Thirty-eight different pathogenic or likely pathogenic variants were identified, including 13 new and six recurrent variants. Three large deletions were detected by MLPA only. No mutation was detected in 16 patients. In untranslated, regulatory or in deep intronic MEN1 regions of the 76 MEN1 cases, no point or short indel pathogenic variants were found in untranslated, although 33 benign/likely benign and three new VUS variants were detected. Conclusions Our study documents that point or short indel mutations in non-coding regions of MEN1 are very rare events. Also, tNGS proved to be a highly effective technology for routine genetic MEN1 testing.

Epigenetic regulation in the tumorigenesis of MEN1-associated endocrine cell types

Epigenetic regulation is emerging as a key feature in the molecular characteristics of various human diseases. Epigenetic aberrations can occur from mutations in genes associated with epigenetic regulation, improper deposition, removal or reading of histone modifications, DNA methylation/demethylation and impaired non-coding RNA interactions in chromatin. Menin, the protein product of the gene causative for the multiple endocrine neoplasia type 1 (MEN1) syndrome, interacts with chromatin-associated protein complexes and also regulates some non-coding RNAs, thus participating in epigenetic control mechanisms. Germline inactivating mutations in the MEN1 gene that encodes menin predispose patients to develop endocrine tumors of the parathyroids, anterior pituitary and the duodenopancreatic neuroendocrine tissues. Therefore, functional loss of menin in the various MEN1-associated endocrine cell types can result in epigenetic changes that promote tumorigenesis. Because epigenetic changes are reversible, they can be targeted to develop therapeutics for restoring the tumor epigenome to the normal state. Irrespective of whether epigenetic alterations are the cause or consequence of the tumorigenesis process, targeting the endocrine tumor-associated epigenome offers opportunities for exploring therapeutic options. This review presents epigenetic control mechanisms relevant to the interactions and targets of menin, and the contribution of epigenetics in the tumorigenesis of endocrine cell types from menin loss.

The Importance of an Early and Accurate MEN1 Diagnosis

Multiple Endocrine Neoplasia type 1 (MEN1) is a rare autosomal dominant inherited condition, causing significant morbidity, and a reduction of life expectancy. A timely and accurate diagnosis of MEN1 is paramount to improve disease outcomes. This enables early identification of tumor manifestations allowing timely treatment for reducing morbidity and improving survival. Current management of MEN1 poses two challenges regarding the MEN1 diagnosis: diagnostic delay and the issue of phenocopies. A delay in diagnosis can be caused by a delay in identifying the index case, and by a delay in identifying affected family members of an index case. At present, lag time between diagnosis of MEN1 in index cases and genetic testing of family members was estimated to be 3.5 years. A subsequent delay in diagnosing affected family members was demonstrated to cause potential harm. Non-index cases have been found to develop clinically relevant tumor manifestations during the lag times. Centralized care, monitoring of patients outcomes on a national level and thereby improving awareness of physicians treating MEN1 patients, will contribute to improved care. The second challenge relates to "phenocopies." Phenocopies refers to the 5-25% of clinically diagnosed patients with MEN1in whom no mutation can be found. Up to now, the clinical diagnosis of MEN1 is defined as the simultaneous presence of at least two of the three characteristic tumors (pituitary, parathyroids, or pancreatic islets). These clinically diagnosed patients undergo intensive follow up. Recent insights, however, challenge the validity of this clinical criterion. The most common mutation-negative MEN1 phenotype is the combination of primary hyperparathyroidism and a pituitary adenoma. This phenotype might also be caused by mutations in the CDKN1B gene, causing the recently described MEN4 syndrome. Moreover, primary hyperparathyroidism and pituitary adenoma are relatively common in the general population. Limiting follow-up in patients with a sporadic co-occurrence of pHPT and PIT could reduce exposure to radiation from imaging, healthcare costs and anxiety.

The future: medical advances in MEN1 therapeutic approaches and management strategies

Multiple endocrine neoplasia type 1 is a rare autosomal inherited disorder associated with a high risk for patients to simultaneously develop tumors of the parathyroid glands, duodenopancreatic neuroendocrine tumors and tumors of the anterior pituitary gland. Early identification of MEN1 in patients enables presymptomatic screening of manifestations, which makes timely interventions possible with the intention to prevent morbidity and mortality. Causes of death nowadays have shifted toward local or metastatic progression of malignant neuroendocrine tumors. In early cohorts, complications like peptic ulcers in gastrinoma, renal failure in hyperparathyroidism, hypoglycemia and acute hypercalcemia were the primary causes of early mortality. Improved medical treatments of these complications led to a significantly improved life expectancy. The MEN1 landscape is still evolving, considering the finding of breast cancer as a new MEN1-related manifestation and ongoing publications on follow-up and medical care for patients with MEN1. This review aims at summarizing the most recent insights into the follow-up and medical care for patients with MEN1 and identifying the gaps for future research.