Project description:BackgroundMultiple endocrine neoplasia type 2B (MEN2B) is a rare autosomal dominant syndrome characterized by medullary carcinoma of the early thyroid, pheochromocytoma, and non-endocrine manifestations, such as marfanoid habits and other skeletal abnormalities as well as mucosal neuromas and ganglioneuromatosis of the gastrointestinal tract.Case descriptionA 10-year-old male began follow-up at our service at 3 years of age through pediatric gastroenterology due to intestinal constipation. The mother also reported that the child had painless lesions on the tip of the tongue since birth with progressive worsening. The patient simultaneously began follow-up with pediatric endocrinology due to low gains in weight and height, between which only isolated low weight was found, and the onset of follow-up with the pediatric neurology team due to longstanding headache combined with vomiting, photophobia, and phonophobia as well as a specific reading and writing disorder. The patient was sent to clinical genetics. The child's karyotype was 46, XY (normal). Through a physical examination, the pediatric neurology team identified joint hypermobility, important muscle hypotrophy, gingival hypertrophy, and lipodystrophy. The patient was sent to neurogenetics, initiating a set of general laboratory exams for the investigation of the lipodystrophy and a panel of exams for lipodystrophy, neuropathy, and muscle hypotrophy as well as electroneuromyography. MEN2B due to genetic mutation was confirmed and the patient was sent to the pediatric endocrinology clinic for follow-up. Currently 10 years of age and again with the pediatric endocrinology team for the diagnosis of MEN2B, the investigation of pheochromocytoma and medullary thyroid cancer was initiated.ConclusionsAn additional mutation occurs in most cases of MEN2B. The diagnosis is only established when the child or, in most cases, adolescent presents with medullary thyroid cancer in an advanced and even metastatic stage. However, non-endocrine manifestations, can lead to an early diagnosis and timely intervention. The diagnosis of MEN2B is made with the confirmation of the autosomal dominant genetic mutation or a mutation of the RET gene. In the absence of these mutations, the majority of clinical manifestations should be present.
Project description:Multiple endocrine neoplasia type 1 (MEN1) is an autosomal-dominant tumor syndrome characterized by the occurrence of tumors in multiple endocrine tissues and nonendocrine tissues. The three main endocrine tissues most frequently affected by tumors are parathyroid (95%), enteropancreatic neuroendocrine (50%) and anterior pituitary (40%). Tumors are caused by a heterozygous germline-inactivating mutation in the MEN1 gene (1st hit) followed by somatic inactivating mutation or loss of the normal copy of the gene (2nd hit), leading to complete loss of function of the encoded protein menin. Most of the disease features and tumors are recapitulated in mouse models with heterozygous germline loss of the Men1 gene. Also, tissue-specific tumors are observed in mouse models with homozygous somatic loss of the Men1 gene specifically in MEN1-associated endocrine tissues. Hence, mouse models could serve as possible surrogates for studying MEN1 and related states. To gain insights into MEN1 pathophysiology, menin-interacting partners and pathways have been identified to investigate its tumor suppressor and other functions. Also, the 3D crystal structure of menin has been deciphered which could be useful to reveal the relevance of MEN1 gene mutations and menin's interactions. This chapter covers clinical, genetic and basic findings about the MEN1 syndrome, MEN1 gene and its product protein menin.
Project description:Multiple Endocrine Neoplasia type 1 (MEN1) is a rare autosomal dominant hereditary cancer syndrome presented mostly by tumours of the parathyroids, endocrine pancreas and anterior pituitary, and characterised by a very high penetrance and an equal sex distribution. It occurs in approximately one in 30,000 individuals. Two different forms, sporadic and familial, have been described. The sporadic form presents with two of the three principal MEN1-related endocrine tumours (parathyroid adenomas, entero-pancreatic tumours and pituitary tumours) within a single patient, while the familial form consists of a MEN1 case with at least one first degree relative showing one of the endocrine characterising tumours. Other endocrine and non-endocrine lesions, such as adrenal cortical tumours, carcinoids of the bronchi, gastrointestinal tract and thymus, lipomas, angiofibromas, collagenomas have been described. The responsible gene, MEN1, maps on chromosome 11q13 and encodes a 610 aminoacid nuclear protein, menin, with no sequence homology to other known human proteins. MEN1 syndrome is caused by inactivating mutations of the MEN1 tumour suppressor gene. This gene is probably involved in the regulation of several cell functions such as DNA replication and repair and transcriptional machinery. The combination of clinical and genetic investigations, together with the improving of molecular genetics knowledge of the syndrome, helps in the clinical management of patients. Treatment consists of surgery and/or drug therapy, often in association with radiotherapy or chemotherapy. Currently, DNA testing allows the early identification of germline mutations in asymptomatic gene carriers, to whom routine surveillance (regular biochemical and/or radiological screenings to detect the development of MEN1-associated tumours and lesions) is recommended.
Project description:Multiple Endocrine Neoplasia Type 2 (MEN2) is a rare hereditary complex disorder characterized by the presence of medullary thyroid carcinoma (MTC), unilateral or bilateral pheochromocytoma (PHEO) and other hyperplasia and/or neoplasia of different endocrine tissues within a single patient. MEN2 has been reported in approximately 500 to 1000 families worldwide and the prevalence has been estimated at approximately 1:30,000. Two different forms, sporadic and familial, have been described for MEN2. Sporadic form is represented by a case with two of the principal MEN2-related endocrine tumors. The familial form, which is more frequent and with an autosomal pattern of inheritance, consists of a MEN2 case with at least one first degree relative showing one of the characteristic endocrine tumors. Familial medullary thyroid carcinoma (FMTC) is a subtype of MEN2 in which the affected individuals develop only medullary thyroid carcinoma, without other clinical manifestations of MEN2. Predisposition to MEN2 is caused by germline activating mutations of the c-RET proto-oncogene on chromosome 10q11.2. The RET gene encodes a single-pass transmembrane tyrosine kinase that is the receptor for glial-derived neurotrophic growth factors. The combination of clinical and genetic investigations, together with the improved understanding of the molecular and clinical genetics of the syndrome, helps the diagnosis and treatment of patients. Currently, DNA testing makes possible the early detection of asymptomatic gene carriers, allowing to identify and treat the neoplastic lesions at an earlier stage. In particular, the identification of a strong genotype-phenotype correlation in MEN2 syndrome may enable a more individualized treatment for the patients, improving their quality of life. At present, surgical treatment offers the only chance of cure and therefore, early clinical and genetic detection and prophylactic surgery in subjects at risk are the main therapeutic goal.
Project description:Multiple endocrine neoplasia type 1 (MEN1), a rare tumor syndrome that is inherited in an autosomal dominant pattern, is continuing to raise great interest for endocrinology, gastroenterology, surgery, radiology, genetics, and molecular biology specialists. There have been 2 major clinical practice guidance papers published in the past 2 decades, with the most recent published 8 years ago. Since then, several new insights on the basic biology and clinical features of MEN1 have appeared in the literature, and those data are discussed in this review. The genetic and molecular interactions of the MEN1-encoded protein menin with transcription factors and chromatin-modifying proteins in cell signaling pathways mediated by transforming growth factor β/bone morphogenetic protein, a few nuclear receptors, Wnt/β-catenin, and Hedgehog, and preclinical studies in mouse models have facilitated the understanding of the pathogenesis of MEN1-associated tumors and potential pharmacological interventions. The advancements in genetic diagnosis have offered a chance to recognize MEN1-related conditions in germline MEN1 mutation-negative patients. There is rapidly accumulating knowledge about clinical presentation in children, adolescents, and pregnancy that is translatable into the management of these very fragile patients. The discoveries about the genetic and molecular signatures of sporadic neuroendocrine tumors support the development of clinical trials with novel targeted therapies, along with advancements in diagnostic tools and surgical approaches. Finally, quality of life studies in patients affected by MEN1 and related conditions represent an effort necessary to develop a pharmacoeconomic interpretation of the problem. Because advances are being made both broadly and in focused areas, this timely review presents and discusses those studies collectively.
Project description:BackgroundMultiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome. Early and normative surgery is the only curative method for MEN 2-related medullary thyroid carcinoma (MTC). In patients with adrenal pheochromocytoma, cortical-sparing adrenalectomy (CSA) can be utilized to preserve adrenocortical function.MethodsWe present twenty-six of 33 MEN2 patients underwent prophylactic thyroidectomy with varying neck dissection and eight of 24 MEN2A patients with PHEO underwent adrenal-sparing surgery. Direct sequencing of entire RET exons was performed in all participants.ResultsThe RET mutations (p.C634Y [n = 10], p.C634R [n = 9], p.C634F [n = 2], p.C618Y [n = 8], p.C618R [n = 3], and p.M918T [n = 1]) were confirmed in 20 symptomatic patients and identified in 13 at-risk relatives (RET carriers). Twenty-six of 33 MEN2 patients underwent thyroidectomies with neck dissections; the mean age at the time of the first thyroid surgery and the tumor diameter of the 6 RET carriers was decreased compared with 20 symptomatic patients (P < 0.001 and P = 0.007, respectively), while the disease-free survival was increased (80% vs.10%, P = 0.0001). Seven RET carriers who were declined surgery. One of 20 symptomatic patients with MTC bone metastases after surgery received vandetanib therapy for 20 months and responded well. Additionally, 8 of 24 MEN2A patients who initially had unilateral pheochromocytomas underwent CSA, 1 developed contralateral pheochromo cytomas 10 years later, then also accepted and also agreed to a CSA. None of the patients required steroid replacement therapy.ConclusionsBased on our results, integrated RET screening and the pre-operative calcitonin level is an excellent strategy to ensure earlier diagnosis and standard thyroidectomy. CSA can be utilized to preserve adrenocortical function in patients with pheochromocytomas.
Project description:Objective In patients with multiple endocrine neoplasia type 1 (MEN1), Cushing's syndrome (CS) from endogenous hypercortisolism can result from pituitary, adrenal or other endocrine tumours. The purpose of this study was to characterize the range of presentations of CS in a large series of MEN1 patients.Design Retrospective review of NIH Clinical Center inpatient records over an approximately 40-year period.Patients Nineteen patients (eight males, 11 females) with CS and MEN1.Measurements Biochemical, imaging, surgical and pathological findings.Results An aetiology was determined for 14 of the 19 patients with CS and MEN1: 11 (79%) had Cushing's disease (CD) and three (21%) had ACTH-independent CS owing to adrenal tumours, frequencies indistinguishable from sporadic CS. Three of 11 MEN1 patients with CD (27%) had additional non-ACTH-secreting pituitary microadenomas identified at surgery, an incidence 10-fold higher than in sporadic CD. Ninety-one per cent of MEN1 patients with CD were cured after surgery. Two of three MEN1 patients with ACTH-independent CS (67%) had adrenocortical carcinoma. One patient with adrenal cancer and another with adrenal adenoma were cured by unilateral adrenalectomy. No case of ectopic ACTH secretion was identified in our patient cohort. The aetiology of CS could not be defined in five patients; in three of these, hypercortisolism appeared to resolve spontaneously.Conclusions The tumour multiplicity of MEN1 can be reflected in the anterior pituitary, MEN1-associated ACTH-independent CS may be associated with aggressive adrenocortical disease and an aetiology for CS in MEN1 may be elusive in a substantial minority of patients.
Project description:Multiple endocrine neoplasia (MEN) is characterized by the occurrence of tumors involving two or more endocrine glands within a single patient. Four major forms of MEN, which are autosomal dominant disorders, are recognized and referred to as: MEN type 1 (MEN1), due to menin mutations; MEN2 (previously MEN2A) due to mutations of a tyrosine kinase receptor encoded by the rearranged during transfection (RET) protoncogene; MEN3 (previously MEN2B) due to RET mutations; and MEN4 due to cyclin-dependent kinase inhibitor (CDNK1B) mutations. Each MEN type is associated with the occurrence of specific tumors. Thus, MEN1 is characterized by the occurrence of parathyroid, pancreatic islet and anterior pituitary tumors; MEN2 is characterized by the occurrence of medullary thyroid carcinoma (MTC) in association with phaeochromocytoma and parathyroid tumors; MEN3 is characterized by the occurrence of MTC and phaeochromocytoma in association with a marfanoid habitus, mucosal neuromas, medullated corneal fibers and intestinal autonomic ganglion dysfunction, leading to megacolon; and MEN4, which is also referred to as MENX, is characterized by the occurrence of parathyroid and anterior pituitary tumors in possible association with tumors of the adrenals, kidneys, and reproductive organs. This review will focus on the clinical and molecular details of the MEN1 and MEN4 syndromes. The gene causing MEN1 is located on chromosome 11q13, and encodes a 610 amino-acid protein, menin, which has functions in cell division, genome stability, and transcription regulation. Menin, which acts as scaffold protein, may increase or decrease gene expression by epigenetic regulation of gene expression via histone methylation. Thus, menin by forming a subunit of the mixed lineage leukemia (MLL) complexes that trimethylate histone H3 at lysine 4 (H3K4), facilitates activation of transcriptional activity in target genes such as cyclin-dependent kinase (CDK) inhibitors; and by interacting with the suppressor of variegation 3-9 homolog family protein (SUV39H1) to mediate H3K methylation, thereby silencing transcriptional activity of target genes. MEN1-associated tumors harbor germline and somatic mutations, consistent with Knudson's two-hit hypothesis. Genetic diagnosis to identify individuals with germline MEN1 mutations has facilitated appropriate targeting of clinical, biochemical and radiological screening for this high risk group of patients for whom earlier implementation of treatments can then be considered. MEN4 is caused by heterozygous mutations of CDNK1B which encodes the 196 amino-acid CDK1 p27Kip1, which is activated by H3K4 methylation.
Project description:Multiple endocrine neoplasia type 2 is an autosomal-dominant hereditary cancer syndrome caused by missense gain-of-function mutations of the rearranged during transfection proto-oncogene, which encodes the receptor tyrosine kinase, on chromosome 10. It has a strong penetrance of medullary thyroid carcinomas and can be associated with bilateral pheochromocytoma and primary hyperparathyroidism. Multiple endocrine neoplasia type 2 is divided into three varieties depending on its clinical features: multiple endocrine neoplasia type 2A, multiple endocrine neoplasia type 2B, and familial medullary thyroid carcinoma. The specific rearranged during transfection mutation may suggest a predilection toward a particular phenotype and clinical course of medullary thyroid carcinoma, with strong genotype-phenotype correlations. Offering rearranged during transfection testing is the best practice for the clinical management of patients at risk of developing multiple endocrine neoplasia type 2, and multiple endocrine neoplasia type 2 has become a classic model for the integration of molecular medicine into patient care. Recommendations on the timing of prophylactic thyroidectomy and extent of surgery are based on the classification of rearranged during transfection mutations into risk levels according to genotype-phenotype correlations. Earlier identification of patients with hereditary medullary thyroid carcinoma can change the presentation from clinical tumor to preclinical disease, resulting in a high cure rate of affected patients and a much better prognoses.