MEN1 gene mutation analysis in Italian patients with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN 1) is a familial syndrome characterized by parathyroid, enteropancreatic and pituitary tumors. The gene responsible for this syndrome is localized at chromosomal 11q13 region and DNA markers from this region cosegregate with the disease. The recent identification of the MEN1 gene, encoding for a protein termed menin of 610 amino acids, allowed mutational screening to be performed both in affected families and sporadic cases. To date many different heterozygous mutations, spreading across all the encoding sequence, have been identified in MEN 1 patients with no apparent mutational hot spots or genotype-phenotype correlation. To analyze the genetic alterations of the MEN1 gene occurring in Italian patients we performed mutational screening by Denaturant Gradient Gel Electrophoresis followed by sequencing of exons 2-10 of the MEN1 gene in 27 Italian MEN 1 families and in five sporadic cases. We identified 17 different heterozygous mutations in 60% of analyzed cases. Twelve of these mutations are novel. Two mutations each occurred twice in unrelated families but no evidence of genotype-phenotype correlation can be established for these families. The extension of genetic diagnosis to asymptomatic family members allowed the identification of 10 MEN1 mutant gene carriers, one newly described and nine previously detected by linkage analysis with DNA markers from the 11q13 region. Our findings add new information to the diversity of mutations occurring in the MEN1 gene and confirm that the mutational screening of MEN 1 is a useful approach to detect individuals at higher risk of developing MEN 1-associated tumors.     

A new mutation of the MEN1 gene in an italian kindred with multiple endocrine neoplasia type 1

OBJECTIVE: To report a new mutation of the multiple endocrine neoplasia type 1 (MEN1) gene in an Italian kindred. DESIGN: The study included the female proband, aged 50 years, affected by primary hyperparathyroidism, insulinoma and prolactinoma, and ten relatives. Blood samples were obtained for biochemical and genetic analyses. Clinical screening tests included serum glucose, ionized calcium, intact parathyroid hormone, GH, insulin and prolactin. The coding sequence, including nine coding exons and 16 splice sites, was amplified by PCR and directly sequenced. RESULTS: Two additional cases of primary hyperparathyroidism were identified among the paternal family members. The sequence analysis showed a heterozygous T to C transition at codon 444 in exon 9, resulting in a leucine to proline substitution (L444P) in the patient and in the two paternal family members with primary hyperparathyroidism. The L444P amino acid change was absent in 50 normal subjects. The mutation determined the loss of a BlnI restriction site of the wild-type sequence and the creation of a new restriction EcoRII site. The patient, but not her paternal affected relatives, also had a common heterozygous polymorphism (D418D) in exon 9. CONCLUSIONS: A new MEN1 mutation (L444P) in exon 9 has been identified; this substitution caused the loss of a BlnI restriction site and the creation of a new EcoRII site.     

Cushing's syndrome in multiple endocrine neoplasia type 1

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.     

Thymic carcinoids in multiple endocrine neoplasia type 1

Teh BT (Karolinska Hospital, Stockholm, Sweden). Thymic carcinoids in multiple endocrine neoplasia type 1 (Minisymposium: MEN & VHL). J Intern Med 1998; 243 : 501–4.
Thymic carcinoid is a rare malignancy with about 150 cases reported to date. It is associated with multiple endocrine neoplasia type 1 (MEN-1), but compared with other MEN-1-related neoplasia little is known about it. We have recently described and studied 20 MEN-1-related cases and found that up to 25% of all reported thymic carcinoids are MEN-1 related. It is an insidious tumour not associated with Cushing's syndrome or carcinoid syndrome. Local invasion, recurrence and distant metastasis are common with no known effective treatment. Its male predominance, the absence of loss of heterozygosity (LOH) in the MEN1 region, clustering in some MEN-1 families and the findings of different MEN1 mutations in these clustered families suggest the involvement of additional aetiological factors. We propose that computed tomography (CT) or magnetic resonance imaging (MRI) of the chest should be included as part of the clinical workup for all MEN-1 patients. Prophylactic thymectomy should be considered during subtotal or total parathyroidectomy on MEN-1 patients to reduce the risk of this malignancy.     

Experience with multiple endocrine neoplasia type 1 screening

Abstract. Screening for multiple endocrine neoplasia type 1 (MEN1) may be conducted for a variety of reasons. The principal aims may be more or less scientific, such as early identification of the trait. Other reasons for screening comprise attempts to avoid endocrine morbidity and possibly forthcoming problems from malignant transformation, as well as attempts to identify and treat gene carriers with a clinically overt disease. Several reports have substantiated the diagnostic yield from screening efforts among MEN1 kindreds. Such increases in detection of the disease ideally should be accompanied by enhanced rates of survival in order to fully justify an unlimited search for the trait. However, studies are lacking a clearly verifying reduction of mortality from the detection of presymptomatic MEN1 individuals. While waiting for the results of survival studies in progress, the generally prevailing opinion favours widespread screening because of the evidently decreased morbidity resulting from early diagnosis of the MEN1 trait, which apparently persists even during decades of follow-up. This paper presents the clinical features of the disease and experience derived from a prospective screening programme for MEN1 detection.     

Candidate genes for multiple endocrine neoplasia type 1

Abstract. The aim of this study was to isolate and characterize candidates for the multiple endocrine neoplasia type 1 (MEN1) gene. The development of tumours related to MEN1 is associated with somatic deletions involving the MEN1 locus, suggesting inactivation of a tumour-suppressor gene in this region. We have isolated five cDNA candidates located within the 900 kb remaining for the MEN1 gene, determined their sequence, and characterized their expression in normal tissues and several endocrine tumours. One of the candidates, encoding for phospholipase C-β3, showed properties consistent with the idea of a tumour-suppressor gene.     

一个多发性内分泌腺瘤病1型家系MEN1基因突变的研究

目的 检测一个多发性内分泌腺瘤病1型家系的MEN1基因突变情况.方法 提取12名家系成员外周血基因组DNA,对MEN1基因所有10个外显子进行聚合酶链反应及产物直接测序,亚克隆测序鉴定其杂合性.结果 家系中1例病理确诊甲状旁腺增生的患者存在MEN1基因第10外显子突变1649_1650insC,导致密码子514发生移码突变,另外筛查出2名家系成员也为该突变携带者,临床检测符合MEN1诊断标准.结论 在多发性内分泌腺瘤病1型中国人家系中检测出MEN1基因杂合突变1649_1650insC,该突变在中国人尚未见报道,同时,对家系成员进行基因筛查可以早期诊断该疾病.     

Gonadotroph tumor associated with multiple endocrine neoplasia type 1

Although anterior pituitary tumors constitute a main clinical feature of multiple endocrine neoplasia type 1 (MEN1), and most types of pituitary tumors have been associated with MEN1, gonadotroph tumors have not previously been recognized clinically as part of this syndrome. We report here a woman who presented with ovarian hyperstimulation due to a gonadotroph tumor that was confirmed biochemically and immunohistochemically. She then developed hyperparathyroidism, and she was found to have three hypercellular parathyroid glands. Subsequently, she developed a temporal lobe metastasis of the gonadotroph tumor, demonstrating that it was a gonadotroph carcinoma. The diagnosis of MEN1 was confirmed by finding a deletion mutation (c.307delC) on the second exon of the MEN1 gene that predicts truncation of the resulting menin protein 15 codons downstream from the deletion (p.Leu103fsX15). This case illustrates that gonadotroph tumors, like other pituitary tumors, can be part of MEN1. The clinical implications of this case are that the clinical and biochemical features of gonadotroph tumors should be considered when evaluating patients for MEN1, and MEN1 should be considered in patients who have gonadotroph tumors.     

Atypical thymic carcinoid in multiple endocrine neoplasia type 1 syndrome

An asymptomatic, non-smoker patient carrier of a multiple endocrine neoplasia syndrome type 1 (MEN1) mutation was diagnosed with invasive atypical thymic carcinoid tumor. After surgical treatment the tumor reappeared albeit without metastasis. Thymic carcinoid is a well-known cause of mortality in MEN1, and usually metastatic disease is present at diagnosis. Male sex, smoking, and previous hyperparathyroidism probably play a role in the pathogenesis of this neoplasia.     

Biliary tree gastrinomas in multiple endocrine neoplasia type 1 syndrome

AIM:To describe our patients affected with ectopic biliary tree gastrinoma and review the literature on this topic.METHODS:Between January 1992 and June 2012,28 patients affected by duodenopancreatic endocrine tumors in multiple endocrine neoplasia type 1(MEN1)syndrome underwent surgery at our institution.This retrospective review article analyzes our experience regarding seventeen of these patients subjected to duodenopancreatic surgery for Zollinger-Ellison syndrome(ZES).Surgical treatment consisted of duodenopancreatectomy(DP)or total pancreatectomy(TP).Regional lymphadenectomy was always performed.Any hepatic tumoral lesions found were removed during surgery.In MEN1 patients,removal of duodenal lesions can sometimes lead to persistence or recurrence of hypergastrinemia.One possible explanation for this unfavorable outcome could be unrecognized ectopic localization of gastrin-secreting tumors.This study described three cases among the seventeen patients who were found to have an ectopic gastrinoma located in the biliary tree.RESULTS:Seventeen MEN1 patients affected with ZES were analyzed.The mean age was 40 years.Fifteen patients underwent DP and two TP.On histopathological examination,duodeno pancreatic endocrine tumors were found in all 17 patients.Eighty-one gastrinomas were detected in the first three portions of the duodenum.Only one gastrinoma was found in the pancreas.The mean number of gastrinomas per patient was 5(range 1-16).Malignancy was established in 12 patients(70.5%)after lymph node,liver and omental metastases were found.Three patients exhibited biliary tree gastrinomas as well as duodenal gastrinoma(s).In two cases,the ectopic gastrinoma was removed at the same time as pancreatic surgery,while in the third case,the biliary tree gastrinoma was resected one year after DP because of recurrence of ZES.CONCLUSION:These findings suggest the importance of checking for the presence of ectopic gastrinomas in the biliary tree in MEN1 patients undergoing ZES surgery.     

Germline and somatic mutation of the gene for multiple endocrine neoplasia type 1 (MEN1)

Marx SJ, Agarwal SK, Kester MB, Heppner C, Kim YS, Emmert-Buck MR, Debelenko LV, Lubensky IA, Zhuang Z, Guru SC, Manickam P, Olufemi SE, Skarulis MC, Doppman JL, Alexander RH, Liotta LA, Collins FS, Chandrasekharappa SC, Spiegel AM, Burns AL (National Institutes of Health, Bethesda, USA). Germline and somatic mutation of the gene for multiple endocrine neoplasia type 1 ( MEN1 ) (Minisymposium: MEN & VHL). J Intern Med 1998; 243 : 447–53.
Dideoxyfingerprinting was used to screen for germline and somatic MEN1 mutations. This method, applied to a panel of germline DNA from 15 probands with multiple endocrine neoplasia type 1 (MEN-1), allowed confident discovery of the MEN1 gene. Germline MEN1 mutation has been found in 47 out of 50 probands with familial MEN-1, in 7 out of 8 cases with sporadic MEN-1, and in 1 out of 3 cases with atypical sporadic MEN-1. Germline MEN1 mutation was not found in any of five probands with familial hyperparathyroidism. Somatic MEN1 mutations were found in 7 out of 33 parathyroid tumours not associated with MEN-1. Allowing for repeating mutations, a total of 47 different germline or somatic MEN1 mutations have been identified. Most predict inactivation of the encoded 'menin' protein, supporting expectations that MEN1 is a tumour suppressor gene. The 16 observed missense mutations were distributed across the gene, suggesting that many domains are important to its as yet unknown functions.     

A mouse model of multiple endocrine neoplasia, type 1, develops multiple endocrine tumors

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant cancer syndrome, characterized primarily by multiple tumors in the parathyroid glands, endocrine pancreas, and anterior pituitary. Other tumors, including gastrinoma, carcinoid, adrenal cortical tumors, angiofibroma, collagenoma, and lipoma, also occur in some patients. Individuals with MEN1 almost always have loss-of-function mutations in the MEN1 gene on chromosome 11, and endocrine tumors arising in these patients usually show somatic loss of the remaining wild-type allele. To examine the role of MEN1 in tumor formation, a mouse model was generated through homologous recombination of the mouse homolog Men1. Homozygous mice die in utero at embryonic days 11.5-12.5, whereas heterozygous mice develop features remarkably similar to those of the human disorder. As early as 9 months, pancreatic islets show a range of lesions from hyperplasia to insulin-producing islet cell tumors, and parathyroid adenomas are also frequently observed. Larger, more numerous tumors involving pancreatic islets, parathyroids, thyroid, adrenal cortex, and pituitary are seen by 16 months. All of the tumors tested to date show loss of the wild-type Men1 allele, further supporting its role as a tumor suppressor gene.     

Long-term follow-up of patients with multiple endocrine neoplasia type 1

Whether early surgical treatment of non-functioning pancreas islet cell tumor (NFPT) provides a favorable quality of life and life expectancy in patients with multiple endocrine neoplasia type 1 (MEN1) remains controversial. We analyzed the long-term clinical courses and surgical outcomes of 14 Japanese patients with MEN1-associated NFPTs. NFPTs smaller than 20 mm in diameter did not show any apparent growth over a long monitoring period. Furthermore, these small NFPTs did not metastasize to regional lymph nodes or the liver. On the other hand, the development of additional NFPTs or metastasis was found in five of six patients with large (35 mm or larger) NFPTs. Among the seven patients who underwent a partial pancreatectomy, six patients developed impaired glucose tolerance or diabetes. The accumulation of more prospective data is needed to clarify the optimal surgical indications for patients with NFPTs, especially among the Japanese population, which has a relatively low insulin secretion potency compared with non-Hispanic white and African-American populations.