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PubMed2000

Pituitary macroadenoma in a 5-year-old: an early expression of multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN 1) is associated with parathyroid, enteropancreatic, pituitary, and other tumors. The MEN1 gene, a tumor suppressor, is located on chromosome 11. Affected individuals inherit a mutated MEN1 allele, and tumorigenesis in specific tissues follows inactivation of the remaining MEN1 allele. MEN 1-associated endocrine tumors usually become clinically evident in late adolescence or young adulthood, as high levels of PTH, gastrin, or PRL. Because each of these tumors can usually be controlled with medications and/or surgery, MEN 1 has been regarded mainly as a treatable endocrinopathy of adults. Unlike in MEN 2, early testing of children in MEN 1 families is not recommended. We report a 2.3-cm pituitary macroadenoma in a 5-yr-old boy with familial MEN 1. He presented with growth acceleration, acromegaloid features, and hyperprolactinemia. We tested systematically to see whether his pituitary tumor had causes similar to or different from a typical MEN 1 tumor. Germ line DNA of the propositus and his affected relatives revealed a heterozygous point mutation in the MEN1 gene, which leads to a His139Asp (H139D) amino acid substitution. The patient had no other detectable germ-line mutations on either MEN1 allele. DNA sequencing and fluorescent in situ hybridization with a MEN1 genomic DNA sequence probe each demonstrated one copy of the MEN1 gene to be deleted in the pituitary tumor and not in normal DNA, proving MEN1 "second hit" as a tumor cause. Gsalpha mutation, common in nonhereditary GH-producing tumors, was not detected in this tumor. We conclude that this pituitary macroadenoma showed molecular genetic features of a typical MEN 1-associated tumor. This patient represents the earliest presentation of any morbid endocrine tumor in MEN 1. A better understanding of early onset MEN 1 disease is needed to formulate recommendations for early MEN 1 genetic testing.

Adenoma↗

PubMed1997

Germline mutations of the MEN1 gene in Japanese kindred with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant familial cancer syndrome. The responsible gene MEN1 has recently been isolated, and its germline mutations have been identified in affected individuals in the United States, Canada and Europe. We screened for MEN1 mutations by direct nucleotide sequencing of all protein-coding regions, and identified five distinct germline mutations in five among six Japanese kindreds with familial MEN1 or familial hyperparathyroidism. The mutations were dispersed across the gene. These findings suggest that, because of the absence of an obvious founder effect, the entire MEN1 gene region should be examined for germline mutations in the probands of MEN1 and related syndromes in Japanese families.

DNA, Neoplasm↗

PubMed1998

A large germline deletion of the MEN1 gene in a family with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN1) is a familial cancer syndrome inherited as an autosomal dominant trait. Various heterozygous germline mutations of the responsible gene, MEN1, have been identified within its exons in many, but not all, affected individuals. We here demonstrate, by DNA polymorphism analysis and gene dosage analysis with polymerase chain reaction (PCR), a large heterozygous germline MEN1 deletion in a kindred with MEN1, in whom no mutation could be detected in the PCR-amplified exons. The deletion spanned an at least 7 kb region containing the entire MEN1 gene. These findings indicate that a large germline deletion of the MEN1 gene, which escapes detection in PCR-based sequence analysis, should be considered as a potential cause of MEN1.

Chromosome Deletion↗

PubMed1997

Menin mutations in patients with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN-1) is a familial cancer syndrome with parathyroid, pituitary and enteropancreatic tumors. The disease phenotype segregates with markers on chromosome 11q13. Very recently a new gene was cloned from this region and was found to carry mutations in 14 of 15 unrelated MEN-1 patients. The gene was termed menin and is predicted to code for a tumor suppressor protein of 610 amino acids, but its precise function is totally unknown. To confirm this finding we used PCR from genomic DNA and direct sequencing to analyze exons 2 through 10 of the menin gene in eight patients from four pedigrees with MEN-1 syndrome or an affected relative. We identified four different heterozygous mutations, three of them are novel: one nonsense mutation, one large deletion of 32 bp and two insertions, all of them located in exon 2. Our results confirm that patients with MEN-1 carry mutations in the menin gene.

Adult↗

PubMed1992

Practical guidelines for DNA-based testing in multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant predisposition to neoplastic lesions of the parathyroid glands, the neuroendocrine pancreas, and the anterior pituitary gland. The predisposing genetic defect was localized to the long arm of chromosome 11 by genetic linkage analysis in three affected families. By analyzing six MEN 1 families with 14 DNA marker systems located close to the MEN 1 gene, we have developed a method to identify carriers of the MEN 1 predisposition. We describe practical aspects of such DNA-based diagnostic procedures.

Blotting, Southern↗

PubMed1991

Genetic and clinical characteristics of multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN 1) is an inherited disorder of autosomal-dominant type encompassing tumors of the parathyroid glands, anterior pituitary and endocrine pancreas. The genetic defect responsible for MEN 1 maps to the long arm of chromosome 11 (11q13). Constitutional heterozygosity for the MEN 1 region is lost in proliferating pancreatic endocrine and parathyroid tissue, which suggests that the MEN 1 gene belongs to the group of tumor suppressor genes (antioncogenes). Genetic screening by linkage analysis using RFLP markers allows selection of gene carriers with high degree of accuracy and makes it possible to concentrate the laborious biochemical screening efforts to family members at risk of developing the MEN 1 syndrome. Biochemical screening of the MEN 1 lesions in young asymptomatic individuals decreases the age at diagnosis with many years (decades) and therapeutic intervention can be instituted early. Although it still remains to be established whether early intervention will have an impact on mortality, our long-term experience with 20 MEN 1 kindreds suggests a reduced morbidity as a result of thorough biochemical screening.

Adult↗

PubMed1996

Prolactinoma presenting in identical twins with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type one (MEN 1) is characterized by tumours of the parathyroid glands, pancreatic islet cells and the anterior pituitary and follows an autosomal dominant pattern of inheritance. We report identical twins born to a family known to have the MEN 1 syndrome. The twins were identical until puberty. The first twin underwent puberty normally; the second, however, suffered an early pubertal arrest and was subsequently found to have a prolactinoma. Both were also subsequently shown to have primary hyperparathyroidism. Genetic studies have since confirmed the twins identical for the affected haplotype and show that this is inherited from the father who also has MEN 1. The gene for MEN 1 has now been localized to the long arm of chromosome 11. The current hypothesis is that expression of the syndrome involves two separate genetic mutations. The first mutation is inherited and thus present in all cells but the tumour manifests itself in the endocrine tissue only after a second mutation that represents elimination of the normal allele. In the case described the twins are proven genetically identical. The marked phenotypic difference between the two must, by inference, represent a second somatic mutation and is further supportive evidence of the two-mutation model of tumour expression.

Adolescent↗

PubMed2004

Hypermutability in a Drosophila model for multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type I (MEN1) is an autosomal dominant cancer predisposition syndrome, the gene for which encodes a nuclear protein, menin. The biochemical function of this protein has not been completely elucidated, but several studies have shown a role in transcriptional modulation through recruitment of histone deacetylase. The mechanism by which MEN1 mutations cause tumorigenesis is unknown. The Drosophila homolog of MEN1, Mnn1, encodes a protein 50% identical to human menin. In order to further elucidate the function of MEN1, we generated a null allele of this gene in Drosophila and showed that homozygous inactivation results in morphologically normal flies that are hypersensitive to ionizing radiation and two DNA cross-linking agents, nitrogen mustard and cisplatinum. The spectrum of agents to which mutant flies are sensitive and analysis of the molecular mechanisms of this sensitivity suggest a defect in nucleotide excision repair. Drosophila Mnn1 mutants have an elevated rate of both sporadic and DNA damage-induced mutations. In a genetic background heterozygous for lats, a Drosophila and vertebrate tumor suppressor gene, homozygous inactivation of Mnn1 enhanced somatic mutation of the second allele of lats and formation of multiple primary tumors. Our data indicate that Mnn1 is a novel member of the class of autosomal dominant cancer genes that function in maintenance of genomic integrity, similar to the BRCA and HNPCC genes.

Animals↗

PubMed2005

Multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia-1 (MEN-1) is an autosomal dominant inherited syndrome that occurs due to inactivating mutations of the MEN1 gene locus, coding for a tumor-suppressor protein, menin. The components of MEN-1 are hyperparathyroidism due to multiple parathyroid adenomas, pancreatic neuroendocrine tumors, and pituitary adenomas, in addition to some less common neoplastic manifestations. Care of people with MEN-1 requires knowledge of the problems that may arise, and the best approaches to detect and care for the manifestations of this incurable, but manageable, disease.

Adenoma↗

PubMed1994

Family screening in multiple endocrine neoplasia type 1 (MEN 1).

Multiple endocrine neoplasia type 1 is an autosomal dominantly inherited disorder predisposing to development of neoplastic lesions in the parathyroid glands, the neuro-endocrine pancreas-duodenum and the anterior pituitary. The genetic defect was mapped to the centromeric region of the long arm of chromosome 11, based on studies of somatic deletions in MEN 1-associated tumours and linkage analysis in affected families. Combined family and tumour analyses have shown that tumourigenesis in MEN 1 involves loss of the wild type chromosome, indicating that the putative MEN 1 gene is a tumour suppressor gene. Based on results from linkage analysis in more than 40 MEN 1 families, presymptomatic testing for MEN 1 using DNA polymorphisms can now be performed with high accuracy. Hence, biochemical screening programmes can focus on individuals at risk, in order to identify early signs of tumour development.

Chromosomes, Human, Pair 11↗

PubMed2001

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.

Adenoma↗

PubMed1990

Loss of heterozygosity of markers on chromosome 11 in tumors from patients with multiple endocrine neoplasia syndrome type 1.

Multiple endocrine neoplasia type 1 is an autosomal dominant condition characterized by the development of parathyroid hyperplasia, pituitary adenomas, and pancreatic islet cell tumors. Recently the gene for multiple endocrine neoplasia type 1 was mapped to the long arm of chromosome 11 between the loci PGA and INT2. We tested the hypothesis that tumor development is the result of a somatic deletion that unmasks a constitutional mutation. By investigating DNA isolated from tumors and somatic tissues in 12 patients from 4 different families with multiple endocrine neoplasia type 1, we found loss of heterozygous markers mapped to 11q13 in 9 (82%) of 11 informative tumors. In contrast, we were unable to identify allelic loss from other chromosomes using a variety of informative probes. This high incidence of chromosomal deletion of 11q13 suggests that this region is important in the oncogenesis of this disorder.

Chromosome Deletion↗

PubMed2002

Genotype-phenotype analysis in multiple endocrine neoplasia type 1.

HYPOTHESIS: Multiple endocrine neoplasia type 1 (MEN 1) syndrome is an autosomal dominant disorder caused by germline mutations in the MEN1 gene and characterized by multiple endocrine tumors, most notably in the parathyroid glands, pituitary, and pancreas. The syndrome demonstrates variable expressivity and considerable genetic heterogeneity. Patient data were examined for possible associations between genotype and phenotype. DESIGN: We reviewed recorded medical data from 1975 to 2001 on patients with MEN 1 and compared specific types and locations of MEN1 gene mutations with manifestations of the syndrome. PATIENTS AND RESULTS: We identified 109 affected patients from 24 MEN 1 kindreds. The phenotypic expression of MEN 1 in affected individuals included hyperparathyroidism in 74%, pancreatic endocrine tumors in 51%, and pituitary tumors in 35%. Twelve of 14 insulinomas occurred in patients with pituitary tumors. Mutation analysis was completed in 14 of 24 kindreds (80 of the 109 patients). Mutations were most common in exons 2 (31%), 9 (15%), and 10 (23%). All 21 patients with frameshift mutations (and known pancreatic endocrine tumor status) had such tumors. Pituitary tumors were associated with frameshift mutations in exon 2. CONCLUSIONS: The type and location of MEN1 mutations may be associated with the phenotypic expression of specific tumors. Such information may assist in the genetic counseling and surveillance of at-risk patients. A specific genotype-phenotype correlation is unlikely because of the heterogeneity of the mutations in the MEN1 gene.

Adult↗

PubMed1997

A transcript map for the 2.8-Mb region containing the multiple endocrine neoplasia type 1 locus.

Multiple endocrine neoplasia type 1 (MEN 1) is an inherited cancer syndrome in which affected individuals develop multiple parathyroid, enteropancreatic, and pituitary tumors. The locus for MEN1 is tightly linked to the marker PYGM on chromosome 11q13, and linkage analysis places the MEN1 gene within a 2-Mb interval flanked by the markers D11S1883 and D11S449. Loss of heterozygosity studies in MEN 1 and sporadic tumors suggest that the MEN1 gene encodes a tumor suppressor and have helped to narrow the location of the gene to a 600-kb interval between PYGM and D11S449. Focusing on this smaller MEN1 interval, we have identified and mapped 12 transcripts to this 600-kb region. A precise ordered map of 33 transcripts, including 12 genes known to map to this region, was generated for the 2.8-Mb D11S480-D11S913 interval. Fifteen candidate genes (of which 10 were examined exhaustively) were evaluated by Southern blot and/or dideoxy fingerprinting analysis to identify the gene harboring disease-causing mutations.

Chromosome Mapping↗

PubMed1998

Menin mutations in the diagnosis and prediction of multiple endocrine neoplasia type 1.

INTRODUCTION: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the development of multiple endocrine adenomas, typically in the pancreas, anterior pituitary, and parathyroid glands. The disease is associated with germ-line mutations of the menin gene, a putative tumor-suppressor gene located on human chromosome 11q13. METHODS: To facilitate the diagnosis and prediction of MEN1 in patients and their relatives, we developed a molecular two-step strategy to screen for menin gene mutations. DNA fragments covering the entire menin coding sequence are generated from patient cDNA by polymerase reaction (PCR) and subsequently analyzed by single-strand conformational polymorphism electrophoresis (SSCP). Fragments with aberrant SSCP migration are DNA-sequenced to directly characterize menin mutations. In a second diagnostic step, genomic DNA of healthy relatives of the corresponding MEN1 index patient is analyzed by PCR, with only the specific exon amplified harboring the family-specific mutation. Mutation-specific restriction enzyme digestion of this PCR product finally allows the identification of mutation carriers through pathological restriction fragment patterns. RESULTS: Using this approach, we identified an in-frame deletion mutation (delta Tyr Met) located in menin exon 4 (codon 227-228) that co-segregates with the disease phenotype in a large MEN1 family from Southern Germany. CONCLUSION: It is likely that the direct molecular analysis of menin gene mutations will replace the genetic and biochemical screening tests currently used in the clinical management of MEN1 families. In addition, these studies may provide clues to the tumor biology of both sporadic and MEN1-associated endocrine adenomas.

Adult↗

PubMed1996

[Characteristic pathological associations in multiple endocrine neoplasia type 1].

OBJECTIVES: Multiple endocrine neoplasia type 1 (MEN 1) is an inherited disorder characterised by slow progressing tumors of the parathyroids, of the endocrine pancreas and of the anterior pituitary. A genetic locus predisposing to this disease has been localised on chromosome 11. Predictive diagnosis of carriers of the defective gene is possible in families using genetic markers at this locus. However, this analysis presupposes a precise identification of affected subjects. Moreover, expression of the disease may vary from one family to the other. The aim of the present study was to define the typical clinical features of the syndrom. METHODS: We assessed retrospectively 26 cases of MEN 1 identified during 20 years in the same medico-surgical center. Among 11 men and 15 women, all those who had a genealogical investigation had a positive family history of MEN 1. RESULTS: Bifocal and trifocal tumors were the main patterns of associations, and were diagnosed at a mean age of 48.6 years. Parathyroid involvement was most frequent and earliest (96% of cases). The second most frequent was pancreatic involvement (69.2% of cases) predominantly manifesting with gastrinomas (N = 13). Multifocal tumors were usually diagnosed before or within 5 years following diagnosis of the first tumor. Among pituitary tumors one case of meningioma was observed, a feature not reported previously. An asymptomatic adrenal involvement was observed in about 1/3 of cases. Other silent tumors (euthyroid nodules, lipomas) were also noted. CONCLUSION: These data suggest that the clinical presentation and course of MEN 1 is homogeneous and are in agreement with the hypothesis of a recessive tumor-suppressor gene expressed in specific endocrine cell lines, suggesting that careful family studies should be conducted when a case of MEN 1 is diagnosed to facilitate early carrier detection among relatives.

Adult↗

PubMed2000

Internally shortened menin protein as a consequence of alternative RNA splicing due to a germline deletion in the multiple endocrine neoplasia type 1 gene.

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominantly inherited cancer syndrome (OMIM 131100), with tumours in several endocrine glands. In 1997 the responsible tumour suppressor gene was identified and recently it was shown that menin, its encoded protein, represses JunD-activated gene expression. Although many MEN 1 patients have been investigated both clinically and genetically, no genotype-phenotype correlation has been found yet. The vast majority of MEN1 gene mutations involve point mutations. We describe a patient in whom a 26 base pair deletion in the MEN1 gene, comprising part of exon 3 and part of intron 3, causes activation of a cryptic donor splice site at the beginning of exon 3. This germline mutation results in an in frame deletion of 105 nucleotides in MEN1 gene mRNA, i.e. an internal deletion of 35 amino acids in the menin protein. Since the deleted region of menin has been implicated in binding to JunD, this may explain the tumourigenic effect of this mutation. The knowledge of this MEN1 gene germline defect, may be used for presymptomatic identification of MEN 1 disease gene-carriers among family-members of this proband. This enables early detection of tumour development, timely treatment and genetic counseling.

Adult↗

PubMed2005

Bronchopulmonary carcinoid in multiple endocrine neoplasia type 1.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal-dominant syndrome associated with neoplasia of pituitary, pancreas, parathyroid, and foregut lineage neuroendocrine tissue. Although enteropancreatic carcinoid has been well described in patients with MEN 1, it was believed that bronchopulmonary carcinoid was relatively uncommon, occurring in approximately 5% of patients. It is unclear whether the increased screening of asymptomatic patients with MEN 1 will facilitate early diagnosis of this tumor and improve patient prognosis. METHODS: The authors reviewed the patient records and, when available, thoracic computed tomographic (CT) images of 129 MEN 1-affected adult members of a single family to determine the prevalence and prognosis of bronchopulmonary nodules and carcinoid. RESULTS: Among 129 patients, a diagnosis of bronchopulmonary carcinoid was noted in the records for 6 individuals (1 male and 5 females; 5%). Thoracic CT scans also were available for review from 32 of those patients. Twelve patients (38%) had pulmonary nodules evident on CT scans. Only hypergastrinemia was significantly more common in patients with pulmonary nodules; otherwise, the spectrum of neoplasia was similar between individuals with and without pulmonary lesions. Histologic diagnoses were available in four patients (three female) with abnormal CT images, and carcinoid was confirmed in each patient. No deaths or distant metastases occurred among the patients despite long-term follow-up (mean, 127 months). CONCLUSIONS: The findings suggested that bronchopulmonary carcinoid is more prevalent in patients with MEN 1 than was recognized previously. Furthermore, the diagnosis did not appear to portend a poor prognosis in the majority of affected patients.

Adult↗