Molecular and biochemical screening for the diagnosis and management of medullary thyroid carcinoma in multiple endocrine neoplasia type 2A.

Patients with Multiple Endocrine Neoplasia (MEN) type 2A are at risk for early medullary thyroid carcinoma (MTC). We performed different screening tests for MTC--a recently reported biochemical screening test using omeprazole-induced calcitonin (CT) stimulation and DNA analysis--in fifteen members of two non-consanguineous Brazilian families with MEN 2A. RET proto-oncogene analysis was carried out by direct DNA sequencing of PCR-amplified products for exons 10 and 11. Family 1 showed a germline mutation (C634Y) in three individuals; a sister and a brother with symptomatic MTC; the former also presented with pheochromocytoma and hyperparathyroidism, and her son was a nine-year-old boy of previously unknown status. Family 2 showed the C634R mutation only in the index case, who presented with cutaneous lichen amyloidosis in addition to MTC, pheochromocytoma and hyperparathyroidism. Neither her parents nor her four brothers showed this genetic abnormality, suggesting a de novo RET proto-oncogene mutation in this patient. The controls and patients presented normal basal gastrin levels and a significant increase after omeprazole. Basal CT levels were elevated in patients with MTC and undetectable in control and asymptomatic family members. No subject showed any increase in CT levels after omeprazole treatment. In conclusion, the two most frequent RET proto-oncogene mutations in MEN 2A are present in Brazilian families. In addition, the specificity of basal and omeprazole-stimulated calcitonin is rather limited, and the efficacy of the omeprazole test still needs to be systematically examined. Therefore, RET proto-oncogene analysis must be the first choice for a screening procedure to identify gene carriers in MEN 2A family members and to permit early prophylactic treatment of MTC.     

Exclusion of ZFM1 as a candidate gene for multiple endocrine neoplasia type 1 (MEN1)

The multiple endocrine neoplasia type 1 (MEN1) locus has been previously localised to 11q13 by combined tumour deletion mapping and linkage studies and a 3.8-cM region flanked by PYGM and D11S97 has been defined. The zinc finger in the MEN1 locus (ZFM1) gene, which has also been mapped to this region, represents a candidate gene for MEN1. The ZFM1 gene, which consists of 14 exons, encodes a 623-amino acid protein and exons 2, 8 and 12 encode the putative nuclear localisation signal, a zinc finger motif, and a proline-rich region, respectively. We have investigated these potentially functional regions for germ-line mutations by single-stranded conformational polymorphism (SSCP) analysis in 64 unrelated MEN1 patients. In addition, we performed DNA sequence analysis of all the 14 exons and 13 of the 26 exon-intron boundaries in four unrelated MEN1 patients. A 6-bp deletion that resulted in the loss of two proline residues at codons 479 and 480 in exon 12 was found in one MEN1 patient. However, this did not co-segregate with MEN1 in the family and represented a rare polymorphism. Analysis by SSCP, DNA sequencing, northern blotting, Southern blotting and pulsed field gel electrophoresis revealed no additional genetic abnormalities of ZFM1 in the other MEN1 patients. Thus, our results indicate that ZFM1 is excluded as a candidate gene for MEN1. Received: 29 October 1996 / Revised: 16 December 1996     

The clinical implications of a positive calcitonin test for C-cell hyperplasia in genetically unaffected members of an MEN2A kindred.

C-cell hyperplasia precedes the development of medullary thyroid carcinoma in multiple endocrine neoplasia type 2A (MEN2A). Identification of abnormal calcitonin levels after a provocative stimulus is a technique that has been widely used to diagnose this preneoplastic condition in an early stage during the development of medullary thyroid carcinoma, when total thyroidectomy is likely to be curative. In a MEN2A kindred, we identified seven individuals with abnormal calcitonin test results, whose carrier state was questionable. Five of these people were thyroidectomized, and C-cell hyperplasia was diagnosed. Four of these individuals were the offspring of a mother who is at risk for the development of MEN2A but who has had normal calcitonin test results throughout the years and of a father who is not at risk but who has had abnormal test results over a period of 10 years, without evidence of progressive elevation. None of these people developed other manifestations of MEN2A. DNA analysis using markers linked to the MEN2A gene demonstrated, with > 99% likelihood, that none of the individuals who could be genotyped was a gene carrier. C-cell hyperplasia due to some mechanism other than the presence of the MEN2A gene may also occur in MEN2A kindreds. DNA analysis offers an important additional tool for proper diagnosis in the clinical management of MEN2A families.     

Genetic screening of endocrine tumour syndromes with DNA probes: the example of medullary thyroid carcinoma

Multiple endocrine neoplasia type 2A (MEN2A) is an autosomal-dominant syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and parathyroid hyperplasia. Recent reports have assigned the locus of MEN2A to the pericentromeric region of chromosome 10. Through the 'Groupe d'Etude des Tumeurs à Calcitonine', we have evaluated the ability to predict the carrier state using DNA probes. Our results suggest that the restriction fragment length polymorphism method can be used to identify individuals at risk within MEN2A families. They may then be followed by conventional endocrine methods for the onset of neoplastic changes, limiting the risk of subsequent metastatic disease. The method also permits the exclusion of further screening for family members at very low risk. Extension of the screening program can now be anticipated for other inherited forms of MTC, such as familial MTC without pheochromocytoma or other endocrinological tumor syndromes such as MEN1 for which the locus has also recently been mapped.     

Clinical and genetic profile of patients with medullary thyroid cancer treated in the Cancer Centre--Institute of Oncology in Warsaw

INTRODUCTION: The aim of this study was to analyse the distribution and frequency of mutations and their correlations with clinical phenotypes of patients with MTC, to reveal the differences between sporadic and familial type of MTC, and to describe the phenotypes of patients. MATERIALS AND METHODS: 212 patients with medullary thyroid cancer (MTC) were treated in Cancer Centre in Warsaw between 1997 and 2005. In most patients, DNA isolated from peripheral blood leukocytes was tested for RET gene mutations by sequencing and accordingly MTC form was assessed. Genetic testing was performed in the relatives of patients with familial MTC in order to distinguish asymptomatic mutation carriers from noncarriers. RESULTS: RET gene mutations were identified in 46 patients (22%). The others were found noncarriers and sporadic MTC was diagnosed. MEN 2A/FMTC syndrome (multiple endocrine neoplasia type 2A/ familial type of MTC) was diagnosed in 44 patients, MEN 2B syndrome (multiple endocrine neoplasia type 2B) in 2 patients. In patients with sporadic and familial MTC, age at diagnosis and multifocal occurrence was analysed, and the results were found to be in accordance with those of other research centres. However, the distribution and frequency of mutations, as well as some clinical data, such as the frequency of pheochromocytoma occurrence as the first manifestation of MEN syndrome, differed from the published data, and further studies are necessary to reveal the reasons of these differences. CONCLUSIONS: DNA testing for RET gene mutations is reliable as a diagnostic tool and therefore it should be performed for screening of all patients with MTC or other diseases of MEN syndrome.     

Characterization of mutations in patients with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by tumors of the parathyroids, pancreatic islets, and anterior pituitary. The MEN1 gene, on chromosome 11q13, has recently been cloned, and mutations have been identified. We have characterized such MEN1 mutations, assessed the reliability of SSCP analysis for the detection of these mutations, and estimated the age-related penetrance for MEN1. Sixty-three unrelated MEN1 kindreds (195 affected and 396 unaffected members) were investigated for mutations in the 2,790-bp coding region and splice sites, by SSCP and DNA sequence analysis. We identified 47 mutations (12 nonsense mutations, 21 deletions, 7 insertions, 1 donor splice-site mutation, and 6 missense mutations), that were scattered throughout the coding region, together with six polymorphisms that had heterozygosity frequencies of 2%-44%. More than 10% of the mutations arose de novo, and four mutation hot spots accounted for >25% of the mutations. SSCP was found to be a sensitive and specific mutational screening method that detected >85% of the mutations. Two hundred and one MEN1 mutant-gene carriers (155 affected and 46 unaffected) were identified, and these helped to define the age-related penetrance of MEN1 as 7%, 52%, 87%, 98%, 99%, and 100% at 10, 20, 30, 40, 50, and 60 years of age, respectively. These results provide the basis for a molecular-genetic screening approach that will supplement the clinical evaluation and genetic counseling of members of MEN1 families.     

Medullary thyroid carcinoma: from molecular studies to clinical decision

The paper is focused on guidelines of practice in inherited medullary thyroid cancer, diagnosed on the basis of DNA analysis. Identification of RET mutation implies further steps of diagnostic procedure, some of them - USG, FNAB and calcitonin level tests - are common for all types of mutation, other are related to ascertained type of mutation. In asymptomatic RET mutation carriers, prophylactic thyroidectomy is indicated. In MEN2B inherited cancer reveals its symptoms quickly and shows dynamic progress. In MEN2A/FMTC the clinical picture is diversified - in some patients the course of disease is mild, however in some other cases the progression of disease and even death occur regardless of the proper treatment. Unfortunately, there are no molecular prognostic markers in medullary thyroid carcinoma. Recent papers and also our own unpublished results show that gene expression profile, is similar in MEN2A and sporadic cancer. This group differs from MEN2B by its expression profile. In conclusion it is to be emphasized that although inherited medullary thyroid carcinoma is a rare disease, the diagnostic algorithm is well established and maximizes the chance for early diagnosis. Moreover, it needs to be stressed that DNA analysis results inform us not only about the necessity of further therapy, but also suggest different ways of proceeding in particular type of mutation.     

Linked markers flanking the gene for multiple endocrine neoplasia type 2A

The inherited cancer syndrome multiple endocrine neoplasia type 2A (MEN2A) has recently been mapped to chromosome 10. We have typed 29 families with this disorder with DNA markers from the pericentromeric region of chromosome 10. Two markers, RBP3 and MCK2, were tightly linked to the MEN2A gene at recombination fractions of less than 3%. Multipoint analysis of the linkage data suggests that the gene is located within a 3-cM interval defined by the markers RBP3/MCK2 on one side and TB14.34 on the other. No evidence for locus heterogeneity was detected in any of the 27 families from 14 countries who were informative for the markers tested. The data confirm and refine the original assignment and provide the basis for presymptomatic screening for this disorder.     

A Novel Deletion Mutation in the Men1 Gene in a Patient with Prolactinoma and a Family History of Pancreatic Tumors

ObjectiveMultiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant tumor syndrome caused by mutations in the MEN1 gene. Mutations in this tumor suppressor gene are often associated with neuroendocrine tumors. Here we describe a novel deletion mutation at codon 304 in the MEN1 gene of a patient with a prolactinoma and strong family history of pancreatic tumors.MethodsWe describe the patient’s clinical course and mutational analysis and review the relevant literature. Results: A 30-year-old pregnant female was referred to our institution’s psychological department for treatment of depression. She had developed a prolactinoma at age 17 and was being treated with 1 mg/week of cabergoline. A medical interview revealed a family history of pancreatic islet cell and other tumors; her mother died of pancreatic cancer, her brother is living with gastrinoma, and her sister died of leiomyosarcoma. Extensive examinations performed after delivery, including laboratory tests and computed tomography (CT) scans, did not reveal any other tumors. Mutational analysis of the MEN1 gene identified a heterozygous deletion mutation (c911_914delAGGT) at codon 304. This mutation produces a frameshift at p.304Lys and might disturb the splicing of intron 6 due to the lack of a donor site. The predicted menin protein from the mutated allele is truncated at amino acid 328.ConclusionWe report a novel deletion mutation (c911_914delAGGT) in the MEN1 gene that was likely associated with the patient’s prolactinoma and her strong family history of pancreatic tumors. (Endocr Pract. 2014; 20:e162-e165)     

Diagnosis by Serendipity: Cushing Syndrome Attributable to Cortisol-Producing Adrenal Adenoma as the Initial Manifestation of Multiple Endocrine Neoplasia Type 1 Due to a Rare Splicing Site Men1 Gene Mutation

ObjectiveTo report a case that highlights the potential for Cushing syndrome to be the first manifestation of multiple endocrine neoplasia type 1 (MEN 1) syndrome and to describe the rare underlying genetic mutation and the heterogeneous manifestations of the syndrome within the same family.MethodsWe present a case report including biochemical and radiologic findings, review family data, and discuss the results of genetic analyses.ResultsA 16-year-old girl who was not known to have any medical illness and had no known family history of MEN 1 syndrome presented with Cushing syndrome attributable to a cortisol-producing adrenal adenoma. During her evaluation, she was found to have primary hyperparathyroidism and a pituitary microprolactinoma. These findings raised the possibility of MEN 1 syndrome. She did not have clinical, biochemical, or radiologic evidence of islet cell pancreatic tumors. Family screening showed that her father had evidence of primary hyperparathyroidism, mild hyperprolactinemia, normal findings on magnetic resonance imaging of the pituitary, and a 1.2- cm nodule in the tail of the pancreas in conjunction with slight elevation of serum insulin and normal gastrin levels. The patient’s 5 siblings had evidence of primary hyperparathyroidism, and 2 of them also had mild hyperprolactinemia. Genetic screening confirmed the presence of a MEN1 gene missense G to A mutation in the patient, her father, and her siblings at the splicing site of intron 6 (IVS6 + 1G > A). This mutation leads to frameshift and truncation of the MEN1 gene.ConclusionIn MEN 1, Cushing syndrome is an extremely rare and usually late manifestation. Most cases are due to corticotropin-producing pituitary adenomas. Although Cushing syndrome generally develops years after the more typical manifestations of MEN 1 appear, it may be the primary manifestation of MEN 1 syndrome. There is considerable heterogeneity in the manifestations of MEN 1, even within a family having the same genetic mutation. (Endocr Pract. 2008;14:595-602)     

Description of the first two seemingly unrelated Greek Cypriot families with a common C618R RET proto-oncogene mutation

Germ-line mutations of the RET proto-oncogene cause three different cancer syndromes: multiple endocrine neoplasia type 2A (MEN2A), multiple endocrine neoplasia type 2B, and familial medullary thyroid carcinoma (FMTC). The objective of the present study was the clinical and molecular characterization of the first two Greek Cypriot families diagnosed with MEN2A and FMTC. The clinical diagnosis of the probands was based on clinical presentation and supported with laboratory findings (calcitonin and carcinoembryonic antigen tumor marker levels). We screened the RET gene by direct DNA sequencing of exons 10, 11, and 16 using genomic DNA as templates. After identification of the mutation, we also developed the amplification refractory mutation system (ARMS) as an alternative method to direct sequencing for genetic diagnosis of 22 additional individuals from both families. We identified the germ-line missense mutation T --> C of codon 618 of exon 10 (C618R) in the probands of both families. By using ARMS, two members of the MEN2A family and five members of the FMTC family were also found positive for the C618R mutation. These are the first seemingly unrelated families in Cyprus investigated clinically and molecularly in detail and shown to transmit this common RET proto-oncogene mutation.     

The Importance of Periodical Screening for Primary Hyperparathyroidism in a Pituitary Tumor Cohort in Searching Patients With MEN1 and Its Genetic Profile

ObjectiveMultiple endocrine neoplasia type 1 (MEN1) is a rare genetic syndrome characterized by parathyroid, anterior pituitary, and/or duodenopancreatic neuroendocrine tumors. Studies have indicated that investigating primary hyperparathyroidism (pHPT) with subsequent genetic screening may be an essential tool for the early diagnosis of MEN1 in patients with pituitary tumors (PTs). This study aimed to investigate the presence of pHPT in patients with PTs and, subsequently, to screen for genetic mutations and related tumors in patients with MEN1 syndrome.MethodsThis study included 255 patients with PTs who were assessed for the presence of MEN1 by serum calcium and parathyroid hormone measurements. Mutation screening of the MEN1, CDKN1B, and AIP genes was performed in the index cases showing the MEN1 phenotype.ResultsFive patients with PTs presented a clinical condition compatible with MEN1. These patients had a younger age of onset and a more severe clinical condition. Genetic analysis identified a frameshift mutation in the MEN1 gene in one of the cases with the MEN1 phenotype, but point mutations in CDKN1B and AIP were not detected in any of these patients.ConclusionOur results show that periodic screening for pHPT in patients with PTs may be useful to detect MEN1 syndrome; thus, it is recommended in those patients with both findings a genetic analysis of MEN1 gene and an additional search of related tumors. By contrast, our data suggest that CDKN1B and AIP mutations do not seem to play a relevant role in the pathogenesis of MEN1.     

Exclusion of the phosphatidylinositol-specific phospholipase C β3 (PLC β3) gene as candidate for the multiple endocrine neoplasia type 1 (MEN 1) gene

Multiple endocrine neoplasia type 1 (MEN 1) is inherited as an autosomal dominant disorder, characterized by hyperplasia and neoplasia in several endocrine organs. The MEN 1 gene, which is most probably a tumor suppressor gene, has been localized to a 900-kb region on chromosome 11q13. The human phosphatidylinositol-specific phospholipase C β3 (PLC β3) gene, which is located within this region, was considered to be a good candidate for the MEN 1 gene. In this study, the structure and expression of the PLC β3 gene in MEN 1 patients were investigated in more detail, to determine its potential role in MEN 1 tumorigenesis. Southern blot analysis, using blood and tumor DNA from affected persons from seven different MEN 1 families, did not reveal structural abnormalities in the PLC β3 gene. To detect possible point mutations, or other small structural aberrations, direct sequencing of PLC β3 cDNAs from two affected persons from two different MEN 1 families was performed, but no MEN 1-specific abnormalities were revealed. Several common nucleotide sequence polymorphisms were detected in these cDNAs, proving that both alleles of the PLC β3 gene were expressed and analyzed. In conclusion, these results exclude the PLC β3 gene as a candidate gene for MEN 1. Received: 20 March 1996     

Exclusion of the phosphoinositide-specific phospholipase Cβ3 (PLCB3) gene as a candidate for multiple endocrine neoplasia type 1

The predisposing genetic defect in multiple endocrine neoplasia type 1 has been assigned to chromosomal region 11q13. Our previous attempts to identify the MEN1 gene have resulted in the isolation of the phospholipase Cβ3 gene from the actual region. PLCB3 plays an important role in signal transduction and, moreover, shows loss of expression in some endocrine tumors, in accordance with a putative tumor suppressor gene function, and thus appears to be an excellent candidate for MEN1. We have therefore undertaken screening for constitutional mutations in individuals from MEN1 families. Several sequence alterations have been discovered, none of them however fulfilling the criteria for a disease-related mutation. We can now exclude PLCB3 from candidacy as the MEN1 gene. Received: 24 July 1996 / Revised: 16 August 1996     

Exclusion of the 13-kDa rapamycin binding protein gene (FKBP2) as a candidate gene for multiple endocrine neoplasia type 1

The MEN1 gene is considered to be a tumour suppressor gene and has been localised to a 1-Mb region of 11q13.1. In this study, we report the physical localisation of the 13-kDa FK506 and rapamycin binding protein gene (FKBP2) to the cosmid marker D11S750, which is located inside the MEN1 region of non-recombination. The product of this gene is involved in signal transduction and is thus a candidate cell growth regulator or tumour suppressor gene. Northern studies have revealed that FKBP2 is expressed in those tissues predisposed to hyperplasia in MEN1; however, single-strand conformation polymorphism analysis and direct sequencing of DNAs from affected members of MEN1 kindreds and sporadic tumour DNAs have been performed and no mutations have been found. These studies exclude FKBP2 as a candidate gene for MEN1.     

Germ-line mutation analysis in patients with multiple endocrine neoplasia type 1 and related disorders.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome predisposing to tumors of the parathyroid, endocrine pancreas, anterior pituitary, adrenal glands, and diffuse neuroendocrine tissues. The MEN1 gene has been assigned, by linkage analysis and loss of heterozygosity, to chromosome 11q13 and recently has been identified by positional cloning. In this study, a total of 84 families and/or isolated patients with either MEN1 or MEN1-related inherited endocrine tumors were screened for MEN1 germ-line mutations, by heteroduplex and sequence analysis of the MEN1 gene-coding region and untranslated exon 1. Germ-line MEN1 alterations were identified in 47/54 (87%) MEN1 families, in 9/11 (82%) isolated MEN1 patients, and in only 6/19 (31.5%) atypical MEN1-related inherited cases. We characterized 52 distinct mutations in a total of 62 MEN1 germ-line alterations. Thirty-five of the 52 mutations were frameshifts and nonsense mutations predicted to encode for a truncated MEN1 protein. We identified eight missense mutations and five in-frame deletions over the entire coding sequence. Six mutations were observed more than once in familial MEN1. Haplotype analysis in families with identical mutations indicate that these occurrences reflected mainly independent mutational events. No MEN1 germ-line mutations were found in 7/54 (13%) MEN1 families, in 2/11 (18%) isolated MEN1 cases, in 13/19 (68. 5%) MEN1-related cases, and in a kindred with familial isolated hyperparathyroidism. Two hundred twenty gene carriers (167 affected and 53 unaffected) were identified. No evidence of genotype-phenotype correlation was found. Age-related penetrance was estimated to be >95% at age >30 years. Our results add to the diversity of MEN1 germ-line mutations and provide new tools in genetic screening of MEN1 and clinically related cases.     

Sequence analysis of the MEN I gene in two patients with multiple cutaneous lipomas and endocrine tumors.

The discovery of mutations of the menin gene in a few multiple endocrine neoplasma type 1 (MEN I)-associated lipomas and loss of heterozygosity (LOH) on chromosome 11q13 in some sporadic lipomas has stimulated the hypothesis that lipomas may belong to the group of sporadic tumors caused by defects of the gene responsible for MEN I. Since it is unclear if the above hypothesis applies to all patients with lipoma or just to specific subsets, we searched to enlarge the database on this topic. For this purpose, we identified two patients with multiple cutaneous lipomas. One had an additional pituitary adenoma and familial presentation of multiple lipomas, the other had recurrent goiter in the setting of a family history of adenomatous goiter. Deoxyribonucleic acid (DNA) was analyzed by complete direct DNA sequencing of all coding exons and splice junctions of the MEN I gene. No mutation was identified in the coding exons of the menin gene. In contrast to former data on sporadic lipomas, these data are the first to render evidence that mutations of the MEN I gene may not be responsible for the formation of multiple lipomas, even if they appear in the context of other endocrine tumors.     

Close linkage of MEN2A with RBP3 locus in Japanese kindreds

Summary The gene responsible for multiple endocrine neoplasia type 2A (MEN2A) has recently been assigned to the pericentromeric region of chromsome 10 in European Caucasian kindreds by linkage analysis using a DNA marker, interstitial retinol-binding protein 3 (RBP3). We have found tight linkage between the MEN2A and RBP3 loci in Japanese MEN2A kindreds. The maximum lod score is 5.19 at a recombination fraction of 0.00. This result suggests that mutation of a certain gene close to RBP3 is responsible for MEN2A irrespective of ethnic backgrounds.