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

Management and Long-Term Follow-Up of Hyperparathyroidism in Multiple Endocrine Neoplasia Type 1: Single Center Experience

Background: Primary hyperparathyroidism (PHPT) in the most common and earliest manifestation of multiple endocrine neoplasia type-1 (MEN1). Epidemiological data have been reported in MEN1 patients but data on long-term follow-up focusing on PHPT are scarce. Methods: In this retrospective cohort study, we included patients diagnosed with MEN1-related PHPT that were under regular follow-up in our institution. Results: Data on 68 patients (39 males), with a mean age at MEN1-diagnosis of 39 ± 13.06 years, were analyzed. Pancreatic neuroendocrine tumors were encountered in 82% (71% nonsecreting) followed by pituitary adenomas in 66% (49% nonsecreting). Mean age at PHPT diagnosis was 35.2 ± 4.0 years. Parathyroidectomy was performed in 57 patients (82.3%), of whom 56% achieved long-term remission, while 12.2% and 31.5% had persistent and recurrent disease, respectively (median follow-up of 4 years; range 1–21 years). Cinacalcet restored serum calcium levels in 33.8%, both as first and as a second line treatment. Permanent hypoparathyroidism occurred in 19.2%. MEN1 pathogenic variants were identified in 77.2% of the tested individuals, but no genotype-phenotype associations were reported. Conclusions: MEN1-related PHPT involves a multiglandular disease and its management remains a therapeutic challenge, as recurrent disease can develop even after 20 years of follow-up. Prolonged follow-up of these patients at referral centers is critical for their optimal management.

Novel Mutations in Serbian MEN1 Patients: Genotype-phenotype Correlation

Background

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant cancer syndrome characterized by the occurrence of primary hyperparathyroidism (PHPT), pituitary adenoma (PA) and pancreatic neuroendocrine tumor (pNET). Whether the underlying mutations in MEN1 gene predict clinical presentation of affected heterozygotes or not, is still a matter of a debate.

Methods

Clinical and genetic analysis of 90 consecutive MEN1 patients was performed in a retrospective, single – center study.

Results

MEN1 mutation was found in 67 (74.4%) patients belonging to 31 different families. Twenty nine different heteozygous mutations were found, including 6 novel point mutations (W220G, 941delG, 1088del7, 1184insA, 1473del10, 1602del17) and one large deletion of exon 8. Truncating mutations predicted development of pNETs (OR=5.8, 95% CI 1.7 – 19.7%) and PHPT (OR=4.3, 95% CI 1.5 – 12.4%).

Conclusions

Large number of novel mutations among MEN1 patients confirmed previously reported data. PNETs and PHPT were more frequent in patients with truncating mutations.

UMD-MEN1 Database: An Overview of the 370 MEN1 Variants Present in 1676 Patients From the French Population

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease caused by mutations in the MEN1 gene characterized by a broad spectrum of clinical manifestations, of which the most frequent are primary hyperparathyroidism, pituitary adenomas, and neuroendocrine tumors.

OBJECTIVE

The aim of this work was to facilitate interpretation of variants and improve the genetic counseling and medical care of families of patients with MEN1.

DESIGN, SETTING, AND PATIENTS

The TENGEN network (Oncogenetics Network of Neuroendocrine Tumors) has interpreted and collected all allelic variants and clinical characteristics of the MEN1-positive patients identified through genetic testing performed in the French population from 1997 to 2015. Patients and their variants were registered in the locus-specific UMD-MEN1 database (www.umd.be/MEN1/).

MAIN OUTCOMES

Variant classification, age-related penetrance, and odds ratios.

RESULTS

A total of 370 distinct variants reported in 1676 patients, including 181 unpublished variants, have been registered. This database analysis revealed a low frequency (6.6%) of benign or likely benign missense variants in MEN1. Eight families (1.9%) had members with familial isolated hyperparathyroidism and harbored the same mutations as that found in families with authentic MEN1. An association existed between large rearrangements and an earlier onset of the disease, whereas no difference was observed between truncating and nontruncating variants.

CONCLUSION

The UMD-MEN1 database provides an exhaustive overview of the MEN1 variants present in the French population. For each variant, a classification is publicly available. Clinical data collections allow the determination of genotype-phenotype correlation and age-related penetrance of lesions in the cohort.

Multiple endocrine neoplasia type 1: analysis of germline MEN1 mutations in the Italian multicenter MEN1 patient database

PURPOSE

Multiple endocrine neoplasia type 1 (MEN1) is caused by germline inactivating mutations of the MEN1 gene. Currently, no direct genotype-phenotype correlation is identified. We aim to analyze MEN1 mutation site and features, and possible correlations between the mutation type and/or the affected menin functional domain and clinical presentation in patients from the Italian multicenter MEN1 database, one of the largest worldwide MEN1 mutation series published to date.

METHODS

The study included the analysis of MEN1 mutation profile in 410 MEN1 patients [370 familial cases from 123 different pedigrees (48 still asymptomatic at the time of this study) and 40 single cases].

RESULTS

We identified 99 different mutations: 41 frameshift [small intra-exon deletions (28) or insertions (13)], 13 nonsense, 26 missense and 11 splicing site mutations, 4 in-frame small deletions, and 4 intragenic large deletions spanning more than one exon. One family had two different inactivating MEN1 mutations on the same allele. Gastro-entero-pancreatic tumors resulted more frequent in patients with a nonsense mutation, and thoracic neuroendocrine tumors in individuals bearing a splicing-site mutation.

CONCLUSIONS

Our data regarding mutation type frequency and distribution are in accordance with previously published data: MEN1 mutations are scattered through the entire coding region, and truncating mutations are the most common in MEN1 syndrome. A specific direct correlation between MEN1 genotype and clinical phenotype was not found in all our families, and wide intra-familial clinical variability and variable disease penetrance were both confirmed, suggesting a role for modifying, still undetermined, factors, explaining the variable MEN1 tumorigenesis.

Mutational and large deletion study of genes implicated in hereditary forms of primary hyperparathyroidism and correlation with clinical features

The aim of this study was to carry out genetic screening of the MEN1, CDKN1B and AIP genes, both by direct sequencing of the coding region and multiplex ligation-dependent probe amplification (MLPA) assay in the largest monocentric series of Italian patients with Multiple Endocrine Neoplasia type 1 syndrome (MEN1) and Familial Isolated Hyperparathyroidism (FIHP). The study also aimed to describe and compare the clinical features of MEN1 mutation-negative and mutation-positive patients during long-term follow-up and to correlate the specific types and locations of MEN1 gene mutations with onset and aggressiveness of the main MEN1 manifestations. A total of 69 index cases followed at the Endocrinology Unit in Pisa over a period of 19 years, including 54 MEN1 and 15 FIHP kindreds were enrolled. Seven index cases with MEN1 but MEN1 mutation-negative, followed at the University Hospital of Cagliari, were also investigated. FIHP were also tested for CDC73 and CaSR gene alterations. MEN1 germline mutations were identified in 90% of the index cases of familial MEN1 (F-MEN1) and in 23% of sporadic cases (S-MEN1). MEN1 and CDC73 mutations accounted for 13% and 7% of the FIHP cohort, respectively. A CDKN1B mutation was identified in one F-MEN1. Two AIP variants of unknown significance were detected in two MEN1-negative S-MEN1. A MEN1 positive test best predicted the onset of all three major MEN1-related manifestations or parathyroid and gastro-entero-pancreatic tumors during follow-up. A comparison between the clinical characteristics of F and S-MEN1 showed a higher prevalence of a single parathyroid disease and pituitary tumors in sporadic compared to familial MEN1 patients. No significant correlation was found between the type and location of MEN1 mutations and the clinical phenotype. Since all MEN1 mutation-positive sporadic patients had a phenotype resembling that of familial MEN1 (multiglandular parathyroid hyperplasia, a prevalence of gastro-entero-pancreatic tumors and/or the classic triad) we might hypothesize that a subset of the sporadic MEN1 mutation-negative patients could represent an incidental coexistence of sporadic primary hyperparathyroidism and pituitary tumors or a MEN1 phenocopy, in our cohort, as in most cases described in the literature.

Nonfunctional pancreatic endocrine tumor in the peripancreatic region in a Chinese patient with multiple endocrine neoplasia type 1

Nonfunctional pancreatic neuroendocrine tumors (NF-pNETs) in patients with multiple endocrine neoplasia type 1 (MEN1), which results from a mutation in the MEN1 gene, are commonly small, multiple tumors located in the pancreatic head and inside the pancreatic parenchyma. We herein describe a 35-year-old woman with bone pain and a 7-year history of a prolactinoma. She was clinically diagnosed with MEN1 based on the presence of the prolactinoma and parathyroid hyperplasia. Abdominal computed tomography revealed a 5-cm mass close to the splenic hilum. This soft tissue tumor, which was located outside the pancreatic parenchyma and the tissue origin of which could not be identified preoperatively, was found to be connected to the pancreatic tail. After resection, histological examination revealed a well-differentiated neuroendocrine tumor of pancreatic origin. Genetic testing revealed a heterozygous transition mutation of guanine to adenine at the coding nucleotide 133 in exon 2 (c.133G>A), resulting in an amino acid substitution of glutamic acid with lysine (E45K) in the MEN1 gene. This patient with MEN1 presented with a clinical condition involving a single non-metastatic NF-pNET located outside the pancreatic parenchyma with a missense mutation in the MEN1 gene, which could easily have been misdiagnosed as an accessory spleen.

Multiple endocrine neoplasia type 1 associated with breast cancer: A case report and review of the literature

Multiple endocrine neoplasia type 1 (MEN1) is a cancer predisposition syndrome that includes a combination of endocrine and non-endocrine tumors. The present study reports a rare case of MEN1 associated with breast cancer with the MEN1 gene mutation. A 45-year-old female was diagnosed with breast cancer subsequent to presenting with a right breast mass. Pre-operative radiological studies indicated right breast cancer with a suspicious metastatic nodule of the lung. Further studies demonstrated bilateral thyroid nodules, a neuroendocrine tumor of the pancreas, paraganglioma, a left adrenal adenoma, gallstones, uterine subserosal myoma and pituitary macroadenoma. Laboratory examinations revealed hypercalcemia, hypophosphatemia and an increased intact parathyroid hormone level. The workup for the suspected MEN syndrome revealed an increased basal plasma level of insulin-like growth factor-1, prolactin and calcitonin, and an increased 24-h urinary free cortisol level. The patient underwent surgical removal of the breast cancer and the tumors of the pancreas, adrenal gland, thyroid and parathyroid glands, uterus, anterior mediastinum and lung. The pathological diagnosis of the resected breast was of invasive ductal carcinoma. Otherwise the pathological diagnosis was of calcitonin-producing pancreatic endocrine carcinoma, adrenal cortical adenoma, bilateral papillary thyroid carcinomas, parathyroid adenomas, uterine leiomyoma with adenomyosis, a thymic carcinoid tumor and lung hamatoma. Gene analysis was performed to determine the association between gene mutations and the development of tumors in this patient, and a germ-line MEN1 gene mutation was consequently detected. It could be assumed that MEN1 syndrome may have possibly predisposed the present patient to breast cancer. However, additional observations and further studies are required to demonstrate this association.

Frequency of germline PTEN mutations in differentiated thyroid cancer

BACKGROUND

Differentiated thyroid cancer (DTC) is seen in 3%-10% of individuals carrying a germline PTEN mutation. Patients with PTEN mutations are at risk for additional neoplasms as are their affected offspring. However, the frequency of PTEN mutations among DTC cases has not been systematically analyzed. The objective of this study was to determine the frequency of PTEN mutations in an unselected group of patients with DTC and to identify whether additional clinical features might indicate the need for referral for genetic counseling and possible testing.

METHODS

We collected personal medical and family history information, head circumference data, and blood from 259 consecutively identified clinic-based patients with DTC, unselected for personal or family history. Individuals were categorized for diagnostic criteria for Cowden syndrome (CS) using the 2009 National Comprehensive Cancer Network (NCCN) guidelines and underwent germline PTEN mutation analysis.

RESULTS

Two of the 259 patients (0.8%), with both follicular thyroid carcinoma and macrocephaly, were found to carry a germline mutation in the PTEN gene. The PTEN mutation frequency in unselected cases of follicular thyroid carcinoma was 4.8%.

CONCLUSION

The frequency of germline pathogenic PTEN mutations in an unselected series of patients with DTC is relatively low, but it is enriched by considering follicular histology and macrocephaly. These results suggest that by adding head circumference to the clinical assessment, thyroid cancer specialists can more effectively identify patients needing referral for cancer genetic services.

MEN1 gene analysis in patients with primary hyperparathyroidism: 10-year experience of a single institution for thyroid and parathyroid care in Japan

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disease. Primary hyperparathyroidism is known to occur at an early age in MEN1 patients. In MEN1 patients, special care regarding not only surgery for hyperparathyroidism but also other MEN1-related tumors is required. Between 1998 and 2007, 482 patients, including 16 whose hyperparathyroidism was discovered by family screening for MEN1, underwent surgical therapy for primary hyperparathyroidism at our institution. We recommended MEN1 gene analysis for patients having one of the following clinicopathological features: 1) age younger than 30 years old; 2) enlargement of multiple glands; 3) coexistence or presence of past history of MEN1-related tumors; or 4) family history of hyperparathyroidism or MEN1-related tumors. Sixty patients had at least one of the above features and were recommended for genetic analysis. Thirty-nine of these patients consented to undergo MEN1 genetic analysis and 16 (41%) showed MEN1 mutation. Pathological examination confirmed multiglandular parathyroid hyperplasia in 15 cases. Subject to this strategy, MEN1 index patients in Japan could be detected efficiently and selected for appropriate therapies for hyperparathyroidism and MEN1-related tumors.

The genetic ascertainment of multiple endocrine neoplasia type 1 syndrome by ancient DNA analysis

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited endocrine cancer syndrome characterised by parathyroid, pancreas, and anterior pituitary tumors. The disease responsible gene, MEN1, was identified in 1997 and localizes to chromosome 11q13 in a minimal 600 kb interval between PYGM and D11S449 loci. About 10-20% of MEN1 patients do not have any mutation in the coding region and/or in the exon-intron junctions of the MEN1 gene. In this case, familial haplotype analysis of the 11q13 region, in at least two generations of affected members, is the only possible genetic ascertainment of the disease. We performed a microsatellite haplotype analysis at 11q13 region in 8 living and 1 deceased member of a MEN1 Italian family without any detected germline mutation of the MEN1 gene. The application of forensic techniques for ancient DNA analysis made it possible to identify the familial disease-associated haplotype and demonstrated that MEN1 disease haplotype family history can be reconstructed even when one or more family members are deceased. Identification of MEN1 disease haplotype is helpful in the clinical management of patients and relatives in families without any mutation of the MEN1 gene. Genetic screening allows the identification of individuals who are at risk before the development of clinical symptoms, limiting invasive annual cancer surveillance only to genetically positive individuals and making it possible to avoid further clinical screenings in non-carriers.

MEN1 gene mutations in Hungarian patients with multiple endocrine neoplasia type 1

OBJECTIVE

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disorder associated with mutations of the MEN1 gene. MEN1 may present as a familial or a sporadic disorder, with multiple endocrine tumours including parathyroid adenomas or hyperplasias, and pancreatic endocrine and pituitary gland tumours. The aim of this study was to examine the prevalence and spectrum of MEN1 gene mutations in Hungarian patients with familial and sporadic MEN1 and in those with a MEN1-related state.

DESIGN

Mutation analysis, using temporal temperature gradient gel electrophoresis and direct sequencing of all coding exons and the corresponding exon-intron boundaries of the MEN1 gene, was performed.

PATIENTS AND MEASUREMENTS

Peripheral blood DNA was obtained from 32 patients (19 index patients with familial or sporadic MEN1 and 13 index patients with familial or sporadic MEN1-related state). First degree relatives were also studied.

RESULTS

Ten different MEN1 gene mutations were identified in 10 index patients, including four novel mutations (A91V, G28A and E26X all in exon 2, and L301R in exon 6). All but one mutation occurred in index patients with familial or sporadic MEN1; the prevalence of mutation was considerably higher in index patients with familial MEN1 (6/6 patients, 100%) than in those with sporadic MEN1 (3/13 patients, 23%). Of the 13 index patients with a MEN1-related state, only one patient with recurrent isolated primary hyperparathyroidism had a MEN1 gene mutation. Family screening indicated mutations in six symptomatic and in one asymptomatic first degree relative.

CONCLUSION

These results confirm previous reports on the high prevalence of novel MEN1 gene mutations among patients with MEN1, and support the questionable efficacy of mutation screening in patients with sporadic MEN1-related states.

Novel MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1

OBJECTIVE

To characterize clinical features and identify MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1 (MEN1). Settings Non-profit academic centre.

PATIENTS

Fourteen Brazilian families with MEN1 and 141 at-risk relatives.

RESULTS

We identified 12 different MEN1 disease-causing mutations, seven of them previously unreported: 308delC; 375del21; 549A>T (I147F); 1243delA; 1348T>G (L413R); 1351T>C (L414P) and 1523G>T (W471C). Families with the recurrent mutations 360delTCTA and L413R were shown to be unrelated by mitochondrial-DNA and Y-chromosome haplotype analyses. Most of the MEN1 single point mutations involved evolutionarily conserved residues, whereas most of the deletion/frameshift changes occurred in GC-rich repetitive regions. Genetic screening of 141 at-risk family members identified 38 MEN1 mutation carriers, 37 (97.4%) of whom had at least one major MEN1-related tumour upon clinical investigation.

CONCLUSIONS

High frequencies of MEN1 gene mutations were detected in Brazilian families with MEN1, including seven new genetic mutations that are predicted to cause inactivation of the MEN1 tumour suppressor gene. Our data underscore the need to implement a systematic MEN1 screening programme in Brazil.

Molecular approaches in the diagnosis of primary immunodeficiency diseases

Over 120 inherited primary immunodeficiency diseases (PIDs) are known to exist. The genes responsible for many of these diseases have also been identified. Recent advances in diagnostic procedures have enabled these to be identified earlier and appropriately treated. While a number of approaches are available to identify mutations, direct sequencing remains the gold standard. This approach identifies the exact genetic change with substantial precision. We suggest that a sensitive and economical approach to mutation detection could be the direct sequencing of cDNA followed by the confirmatory sequencing of the corresponding exon. While screening techniques such as single-stranded conformation polymorphism (SSCP), heteroduplex analysis (HA), denaturing gradient gel electrophoresis (DGGE), and denaturing high-performance liquid chromatography (dHPLC) have proven useful, each has inherent advantages and disadvantages. We discuss these advantages and disadvantages and also discuss the potential of future sequencing technologies such as pyrosequencing, combinatorial sequencing-by-hybridization, multiplex polymerase colony (polony), and resequencing arrays as tools for future mutation detection. In addition we briefly discuss several high-throughput SNP detection technologies.

Multiple endocrine neoplasia type 1

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.

Pancreatectomy in multiple endocrine neoplasia type 1-related gastrinomas and pancreatic endocrine neoplasias

OBJECTIVE

The aim of this study was to evaluate the results of pancreatic resection in pancreatic endocrine neoplasias (PENs) in patients affected by multiple endocrine neoplasia type 1 (MEN1) syndrome.

BACKGROUND

Since these tumors often show an indolent course, the role of diagnostic procedures and type of surgical approach are controversial. Experience with new diagnostic approaches and more aggressive surgery is still limited.

METHODS

Sixteen MEN1 patients were referred to our Surgical Unit (1992-2003) and were operated on for the indications of hypergastrinism, hypoglycemia, and/or pancreatic endocrine neoplasias larger than 1 cm. Zollinger-Ellison syndrome (ZES) was present in 13 patients, 2 of whom experienced a recurrence after previous surgery. Preoperative tumor localization was carried out using ultrasonography (US), computed tomography (CT), endoscopic ultrasonography (EUS), somatostatin receptor scintigraphy (SSRS), or selective arterial secretin injection (SASI). Rapid intraoperative gastrin measurement (IGM) was carried out in 8 patients, and 1 patient also underwent an intraoperative secretin provocative test.

RESULTS

Either pancreatoduodenectomy (PD) or total pancreatectomy (TP) or distal pancreatectomy was performed. There was no postoperative mortality; 37% complications included pancreatic (27%) and biliary (6%) fistulas, abdominal collection (6%), and acute pancreatitis (6%). EUS and SSRS were the most sensitive preoperative imaging techniques. At follow-up, 10 of 13 hypergastrinemic patients (77%) are currently eugastrinemic with negative secretin provocative test, while 3 are showing a recurrence of the disease. All patients affected by insulinoma were cured.

CONCLUSIONS

MEN1 tumors should be considered surgically curable diseases. IGM may be of value in the assessment of surgical cure. Our experience suggests that PD is superior to less radical surgical approaches in providing cure with limited morbidity in MEN1 gastrinomas and pancreatic neoplasias.

Detection of an MEN1 gene mutation depends on clinical features and supports current referral criteria for diagnostic molecular genetic testing

OBJECTIVE

Diagnostic molecular genetic testing for multiple endocrine neoplasia type 1 (MEN1) has been available since the identification of the MEN1 gene in 1997. Mutation screening of the MEN1 gene has been recommended for patients who meet clinical criteria for MEN1 (at least two of the following: parathyroid hyperplasia, pancreatic endocrine tumour or pituitary adenoma) and those in whom a diagnosis of MEN1 is suspected. We examined the appropriateness of these clinical criteria.

PATIENTS AND METHODS

A total of 292 patients were referred for diagnostic testing. The coding region of the MEN1 gene was sequenced in 186 index cases and mutation testing was requested for 106 subjects, including 83 asymptomatic relatives.

RESULTS

MEN1 gene mutations were identified in 68/186 index cases (37%). Twenty-nine of the 60 MEN1 mutations reported are novel. The likelihood of finding a mutation was correlated with the number of MEN1-related tumours (mutation detection rate of 79%, 37% and 15% in patients with three, two and one main MEN1-related tumours; P < or = 0.00001) and increased in the presence of a family history (mutation detection rate of 91%, 69% and 29%vs. 69%, 23% and 0% in sporadic cases with three, two or one main MEN1-related tumours, respectively; P < or = 0.00001). The pick-up rate in the 83% of subjects who met proposed criteria for diagnostic testing was 42%, but in those who did not meet these criteria this fell to 0%.

CONCLUSIONS

The likelihood of finding an MEN1 mutation depends on the clinical features of the patient and their family. This large series supports present referral criteria for diagnostic mutation screening, but suggests that patients with sporadic isolated tumours rarely have MEN1 mutations.

Genetic screening methods for the detection of mutations responsible for multiple endocrine neoplasia type 1

Identification of mutations, which cause genetic diseases can be difficult when the disease is caused by the mutation of a large gene, which contains multiple exons. Detection of these mutations by DNA sequencing can be made more efficient by using mutation detection methods for pre-screening to identify the affected exon and to screen for the presence of already identified mutations in family members. These screening methods include denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE), single-strand conformation polymorphism, conformation-sensitive gel electrophoresis (CSGE), heteroduplex analysis and denaturing high-performance liquid chromatography (DHPLC). We discuss the advantages and shortcomings of these methods by reviewing the results of studies screening for mutations causing multiple endocrine neoplasia type 1 (MEN 1) syndrome, an autosomal dominant disorder characterized by endocrine tumours of the anterior pituitary gland, parathyroid glands, and pancreas. MEN 1 is caused by mutations of the MEN1 gene, a tumour suppressor gene, which contains one untranslated exon and nine exons. Previous studies have identified more than 400 germline and somatic mutations spreading across all the encoding sequence, and found no mutational "hot spot" or genotype-phenotype correlation. The wide diversity of mutations in the entire coding region of the MEN1 gene makes mutation screening time-consuming and expensive. We conclude that combination of mutation detection methods with DNA sequencing enhances the efficiency of identifying pathogenic mutations. However, it should be considered that experimental determination of the optimal electrophoresis conditions, such as using perpendicular electrophoresis to optimise DGGE or TGGE, is more useful than computerized algorithms to calculate these parameters.

Unusual presentation of multiple endocrine neoplasia type 1 in a young woman with a novel mutation of the MEN1 gene

We report an unusual presentation of multiple endocrine neoplasia type 1 (MEN 1) in a young woman who was subsequently proven to have a novel mutation of the MEN1 gene. The young patient, aged 25 years, was investigated for abdominal discomfort and left upper abdominal pain. Her family history was unremarkable, except an unknown disorder of her father causing early death. Abdominal ultrasonography (USG) and computed tomography revealed a giant pancreatic tumor measuring 10 cm in diameter. The diagnosis of a clinically nonfunctioning pancreatic neuroendocrine tumor was established by clinical and other studies, including USG-guided aspiration biopsy and octreotide scintigraphy, and the patient underwent a distal pancreatectomy. Histology proved a well-differentiated multinodular neuroendocrine tumor of the pancreas. During surgery, a subcutaneous lipoma was also removed from the abdominal wall. Two years later, the patient developed primary hyperparathyroidism, and two enlarged parathyroid glands were surgically removed. Magnetic resonance imaging of the pituitary gland was normal. Screening for MEN1 gene mutation by temperature gradient gel electrophoresis revealed heterozygosities in exons 3, 8, and 9, while direct sequencing indicated a novel germline mutation (C354X) resulting in a stop codon in exon 8 and polymorphisms in exon 3 (R171Q) and exon 9 (D418D and L432L). Genetic screening revealed no mutation in living family members. Our unusual case suggests that a multinodular pancreatic neuroendocrine tumor in a young patient may justify screening for MEN 1 syndrome, even in the absence of other endocrinopathy or family history.

A novel germline mutation of MEN 1 gene in a patient with acromegaly and multiple endocrine tumors

Germline mutations of the MEN 1 gene are responsible for multiple endocrine neoplasia type 1 (MEN 1), a dominantly inherited cancer syndrome characterized by tumors of the parathyroids, gastro-intestinal endocrine tissue, anterior pituitary and other endocrine tissues. We report on a 55-yr old woman, presenting with active acromegaly (due to GH-secreting microadenoma), associated to bilateral adrenal adenomatosis and Hürthle-cell thyroid neoplasia. No evidence of hyperparathyroidism or gastrin-secreting tumor was found. Peripheral blood genomic DNA was extracted, amplified by PCR, purified and analyzed by direct sequencing. The analysis revealed a heterozygous mutation in exon 4 of the MEN 1 gene: a G to A missense mutation at codon 229 (CGC-->CAC), which changes arginine to histidine. This mutation causes loss of the Hhal restriction site and can thus be employed for a rapid familiar screening. This case represents a newly recognized germline mutation of the MEN 1 gene.

Multiple endocrine neoplasia type 1 and Zollinger-Ellison syndrome: a prospective study of 107 cases and comparison with 1009 cases from the literature

In patients with multiple endocrine neoplasia type 1 (MEN1), the most common functional pancreatic endocrine tumor (PET) syndrome is Zollinger-Ellison syndrome (ZES). ZES has been well studied in its sporadic form (that is, without MEN1); however, there are limited data on patients with MEN1 and ZES (MEN1/ZES), and the long-term natural history is largely unknown. To address this issue we report the results of a prospective long-term National Institutes of Health (NIH) study of 107 MEN1/ZES patients and compare our results with those of 1009 MEN1/ZES patients in 278 case reports and small series in the literature. Patients were clinically, radiologically, and biochemically evaluated yearly for all MEN1 manifestations (mean follow-up, 10 yr; range, 0.1-31 yr). Compared with patients from the literature, the NIH MEN1/ZES patients more frequently had pituitary (60%) and adrenal (45%) disease and carcinoid tumors (30%), but had equal frequency of hyperparathyroidism (94%), thyroid disease (6%), or lipomas (5%). Twenty-five percent of both the NIH and the literature patients lacked a family history of MEN1; ZES was the initial clinical manifestation of MEN1 in 40%. ZES onset preceded the diagnosis of hyperparathyroidism in 45%. However, ZES was rarely (8%) the only initial manifestation of MEN1 if careful testing was done. ZES occurred before age 40 years in 50%-60% of the current patients, in contrast to older studies. The diagnosis of ZES is delayed 3-5 years from its onset and is delayed as long as in sporadic ZES cases. Pituitary disease and carcinoid tumors (gastric > bronchial, thymic) are more frequent than generally reported, whereas a second functional PET is uncommon. In patients with MEN1/ZES without a family history of MEN1, the MEN1 manifestations are not as severe. This study shows that MEN1/ZES patients differ in many aspects from those commonly reported in older studies involving few MEN1/ZES patients. In this study we have identified a number of important clinical and laboratory features of MEN1/ZES that were not previously appreciated, which should contribute to earlier diagnosis and improve both short- and long-term management.

Frequent occurrence of an intron 4 mutation in multiple endocrine neoplasia type 1

MEN1 is an autosomal dominant disorder characterized by parathyroid, pituitary, and pancreatic tumors. The MEN1 gene is located on chromosome 11q13 and encodes a 610-amino acid protein. MEN1 mutations are of diverse types and are scattered throughout the coding region, such that almost every MEN1 family will have its individual mutation. To further characterize such mutations we ascertained 34 unrelated MEN1 probands and undertook DNA sequence analysis. This identified 17 different mutations in 24 probands (2 nonsense, 2 missense, 2 in-frame deletions, 5 frameshift deletions, 1 frameshift deletional-insertion, 3 frameshift insertions, 1 donor splice site mutation, and a g-->a transition that resulted in a novel acceptor splice site in intron 4). The intron 4 mutation was found in 7 unrelated families, and the tumors in these families varied considerably, indicating a lack of genotype-phenotype correlation. However, this intron 4 mutation is the most frequently occurring germline MEN1 mutation ( approximately 10% of all mutations), and together with 5 others at codons 83-84, 118-119, 209-211, 418, and 516, accounts for 36.6% of all mutations, a finding that indicates an approach for identifying the widely diverse MEN1 mutations.

Genetics of menopause-associated diseases

Menopause is the permanent cessation of menstruation resulting from the loss of ovarian follicular activity. It is estimated that perhaps 50 million women worldwide will go into menopause annually. Atherosclerotic cardiovascular disease, osteoporotic fractures and Alzheimer's dementia are common chronic disorders after menopause, representing major health problems in most developed countries. Apart from being influenced by environmental factors, these chronic disorders recognize a strong genetic component, and there are now considerable clinic evidences that these disorders are related to low hormonal milieu of postmenopausal women. Here, we review up-to-date available data suggesting that genetic variation may contribute to higher susceptibility to four sporadic chronic syndromes such as osteoporosis (OP), osteoarthritis (OA), Alzheimer's disease (AD) and coronary artery disease (CAD). For these four syndromes candidate genes that today appear as major loci in genetic susceptibility encode for proteins specific of a given system, as the vitamin D receptor (VDR) gene for the skeleton and, therefore, OP or angiotensin converting enzyme (ACE) for the cardiovascular system and, therefore, CAD. The investigation of gene polymorphisms in various pathological conditions typical of postmenopause offer an explanation not only of their genetic inheritance but also of their co-segregation in given individuals. In this view, it may be possible to identify a common set of genes whose variants contribute to a common genetic background for these different disorders. Ideal candidates appear genes of the estrogen response cascade [i.e. estrogen receptor (ERs), enzymes involved in estrogen metabolism or co-activators and co-inhibitors]. All together this information may represent the basis both for future recognition of individuals at risk and for the pharmacogenetic driving of drug responsiveness.

Pancreatic endocrine tumors

Pancreatic endocrine tumors are rare but have long held a fascination for clinicians because of the physiologic derangements that they can cause, and the dramatic corrections that can be achieved by appropriate management. In the year reviewed in this article, the literature again demonstrated the ongoing interest and research in this area. In particular, the areas of gastrinoma, insulinoma, and multiple endocrine neoplasia type 1 have received careful attention.