Multiple endocrine neoplasias

Genetic Testing for Successful Cancer Treatment

Cancer genetic testing is a revolutionary medical approach that involves the assessment of genetic markers in asymptomatic individuals to predict their future susceptibility to cancer. This paradigm shift in early detection and intervention has the potential to profoundly alter our strategies for cancer prevention and treatment. One pivotal area where genetic testing can have a significant impact is among families with a hereditary predisposition to cancer. Recent research has seen a surge in the exploration of how individuals perceive their cancer risk within the realm of cancer genetics. This proactive approach to genetic testing allows healthcare professionals to identify family members who may carry the same cancer-related genetic mutations, empowering them to make informed decisions regarding their healthcare and cancer risk management. Genetic testing for cancer-related disorders has significantly improved in accuracy and affordability, potentially revolutionizing monitoring and treatment methods. The expanding knowledge of genetic mutations associated with cancer susceptibility has driven significant progress in cancer therapy. Identifying numerous major cancer susceptibility genes has propelled predictive genetic testing, providing individuals with valuable insights into their genetic predisposition to cancer. While perceived risk plays a vital role in genetic counseling, it is equally essential to offer comprehensive information about the advantages and potential risks associated with genetic testing. Ensuring that individuals have a clear understanding of the benefits and potential drawbacks of genetic testing is imperative for making informed healthcare decisions. In our comprehensive review, researchers explored several critical aspects of genetic testing in the context of cancer, including awareness and knowledge, the communication of cancer genetic risk, genetic testing for inherited cancer syndromes, and the challenges and limitations linked to genetic testing. Through this examination, we aim to illuminate the transformative potential of genetic testing in cancer prevention and treatment.

The Research Landscape of Multiple Endocrine Neoplasia Type 1 (2000–2021): A Bibliometric Analysis

Introduction

This study aimed to investigate the landscape of Multiple Endocrine Neoplasia Type 1 research during the last 22 years using machine learning and text analysis.

Method

In December 2021, all publications indexed under the MeSH term “Multiple Endocrine Neoplasia Type 1” were obtained from PubMed. The whole set of search results was downloaded in XML format, and metadata such as title, abstract, keywords, mesh words, and year of publication were extracted from the original XML files for bibliometric evaluation. The Latent Dirichlet allocation (LDA) topic modeling method was used to analyze specific themes.

Results

This study eventually contained 1,407 publications. Among them, there are 768 (54.58%) case reports and reviews. Text analysis based on MeSH words revealed that the most often studied clinical areas include therapy efficacy, prognosis, and genetic diagnosis. The majority of basic study is focused on genetic alterations. The LDA topic model further identifies three topic clusters include basic research, treatment cluster, and diagnosis cluster. In the basic research cluster, many studies are focused on the expression of Menin. The primary focus of the therapy cluster is pancreatic resections and parathyroidectomy. In the diagnose cluster, the main focus is on Genetic Diagnosis and screening strategies for Hereditary Cancer Syndrome.

Conclusion

The current state of research on MEN1 is far from adequate. Research on rare diseases MEN1 necessitates implementing a broad research program involving multiple centers to advance MEN1 research together.

A large Turkish pedigree with multiple endocrine neoplasia type 1 syndrome carrying a rare mutation: c.1680_1683 del TGAG

BACKGROUND AND AIMS

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome characterized by tumors arising from endocrine glands with no specific genotype-phenotype correlation. Herein, we report the largest Turkish kindred with MEN1 inherited a scarce MEN1 mutation gene.

MATERIALS AND METHODS

Sixty-four year-old man, referred to our gastroenterology outpatient clinic for evaluation of pancreatic mass lesion, was diagnosed with MEN1-syndrome after endoscopic ultrasound guided sampling of the mass revealing pancreatic neuroendocrine tumor (pNET), and accompanying primary hyperparathyroidism (PHPT) and pituitary tumor. Genetic analysis by whole gene Sanger sequencing of MEN1 gene identified a frame-shift mutation in exon 10 (c.1680_1683delTGAG). All the relatives of the index case were proposed for clinical and genetic evaluation for MEN1-syndrome.

RESULTS

Of the 25 relatives of the index case, 17 were diagnosed MEN1-syndrome. Eighteen members among all relatives consented to genetic analysis and 11 had the same mutation as the index case. All the mutation positive members had MEN1, while none of mutation negative subjects had any sign of MEN1-syndrome. The frequencies of PHPT, pNET and pituitary tumors in this kindred were 94.1% (16/17), 29.4% (5/17) and 29.4% (5/17) respectively.

CONCLUSION

We report rare MEN1 gene mutation which was descibed in a single sporadic patient before. It inherited in at least three generations of a large family, which has proven strong dominant effect on MEN1 phenotype. Further researches may be conducted to clarify potential candidacy of this mutation, as a hotspot for MEN1 patients, especially in Turkish population.

Overview of Genetically Determined Diseases/Multiple Endocrine Neoplasia Syndromes Predisposing to Endocrine Tumors

In this chapter, we present an overview of multiple endocrine neoplasia syndromes including their most important clinical and molecular features. Multiple endocrine neoplasia type 1 and 2 syndromes (MEN1 and MEN2) are discussed in detail. Syndromes that are presented in other chapters are only briefly mentioned. We discuss the relevance of germline gene alterations in apparently sporadic endocrine tumors, e.g., medullary thyroid cancer, primary hyperparathyroidism, and neuroendocrine tumors. McCune-Albright syndrome that only exists in non-hereditary, sporadic forms is also discussed in detail, as tumors of several endocrine organs can develop in the same individual.

Genetic analysis of parathyroid and pancreatic tumors in a patient with multiple endocrine neoplasia type 1 using whole-exome sequencing

Background

Multiple endocrine neoplasia type 1 (MEN1) syndrome is an autosomal dominant hereditary disorder characterized by the presence of endocrine tumors affecting the parathyroid, pancreas, and pituitary. A heterozygous germline inactivating mutation in the MEN1 gene (first hit) may be followed by somatic loss of the remaining normal copy or somatic mutations in the MEN1 gene (second hit). Whole-exome sequencing has been successfully used to elucidate the mutations associated with the different types of tumors.

Case presentation

We performed whole-exome sequencing (WES) on three parathyroid tumors, one pancreatic insulinoma, and a blood sample taken from the same patient with MEN1 to study tumor heterogeneity in MEN1 originating from different tumors. We identified a novel frame-shift deletion (c.1382_1383delAG, p.E461GfsX69) in the MEN1 gene using WES, which was confirmed by Sanger sequencing. WES and the SNP array revealed somatic LOH on chromosome 11 in parathyroid tumors (left upper, left lower, and right upper parathyroid). However, we did not detect a somatic MEN1 gene mutation or LOH in the pancreatic insulinoma. WES revealed two somatic functional variants outside the MEN1 gene in the pancreatic insulinoma.

Conclusions

This study revealed heterogeneity among tumors in the same patient with MEN1, suggesting that different tumor-specific tumorigenic mechanisms may contribute to the pathogenesis of MEN1 tumors. The present study supports the clinical applicability of the WES strategy to research on multiple tumor samples and blood.

Electronic supplementary material

The online version of this article (10.1186/s12881-017-0465-9) contains supplementary material, which is available to authorized users.

Hereditary syndromes predisposing to endocrine tumors and their skin manifestations

We often think of the lentiginoses, phacomatoses and other neurocutaneous syndromes as conditions that affect the skin and also predispose to a variety of tumors. However, we rarely think of Peutz-Jeghers syndrome (PJS), Carney complex (CNC), Cowden disease (CD), neurofibromatosis type-1 (NF-1) or tuberous sclerosis (TSC) as conditions that are multiple endocrine neoplasias (MEN). Indeed, all of these conditions predispose to a variety of endocrine tumors, in addition to many other neoplasms. On the other hand, the classic MENs, type 1 and 2 (MEN-1 and MEN-2, respectively) are almost never thought in terms of their skin manifestations. In this review, we present extensively the MEN-1, MEN-2 and PJS syndromes, and briefly refer to CD, NF-1, and TSC. CNC is discussed in another article in this journal issue.

Clinical and Pathological Features of Pheochromocytoma in the Horse: A Multi-Center Retrospective Study of 37 Cases (2007-2014)

Background

Pheochromocytoma is the most common adrenal medullary neoplasm of domestic animals, but it is rare in horses. Antemortem diagnosis in horses is difficult, with clinical signs often being vague or non‐specific.

Objective

The objective of this study was to describe the clinical, laboratory, and pathologic findings of pheochromocytoma in horses.

Animals

Thirty‐seven horses diagnosed with pheochromocytoma based on postmortem examination from 2007 to 2014.

Methods

Retrospective case series.

Results

Pheochromocytoma was identified in 37/4094 horses during postmortem examination. Clinical signs consistent with pheochromocytoma had been observed antemortem in only 7 cases, with the remainder being incidental findings. Colic was the most common presenting complaint (13 of 37 cases) and tachycardia was noted in 95% of cases (median heart rate of 86 bpm in clinical cases). Hyperlactatemia (median, 4.9 mmol/L) and hyperglycemia (median, 184 mg/dL) were the most common clinicopathologic abnormalities. Hemoperitoneum caused by rupture of pheochromocytoma was noted in 4/7 clinical cases. Concurrent endocrine abnormalities (eg, thyroid adenoma, adrenal hyperplasia, pituitary pars intermedia hyperplasia or adenoma, parathyroid C‐cell carcinoma) were found in 27/37 horses, with 8/37 horses having lesions consistent with multiple endocrine neoplasia syndrome as described in humans.

Conclusions

Pheochromocytoma was diagnosed in 0.95% of horses presented for necropsy. The majority of these were incidental findings, but pheochromocytoma was thought to contribute to clinical findings in 19% of cases, and multiple endocrine neoplasms were commonly seen. Usually an incidental finding at necropsy, pheochromocytoma may cause acute death from intraperitoneal exsanguination and should be considered in horses presenting with colic, tachycardia, and hemoperitoneum.

Genetic and epigenetic analysis in korean patients with multiple endocrine neoplasia type 1

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is a familial syndrome characterized by the parathyroid, pancreas and pituitary tumors. Parathyroid tumors are the most common clinical manifestations, occurring in more than 90% of MEN1 patients. Heterozygous germline mutations of the MENIN gene underlie the tumorigenesis in MEN1 and epigenetic alterations along with germline mutations may contribute to tumorigenesis. Here, we investigated the associations between genotype and phenotype in Korean MEN1 patients.

METHODS

We analyzed medical records from 14 unrelated MEN1 patients who had newly confirmed MENIN germline mutations, together with 14 previous reports in Korea. Aberrant DNA methylations were also examined in MEN1-related parathyroid tumors using the Infinium HumanMethylation 450 BeadChip.

RESULTS

Total 28 germline mutations of MENIN were relatively highly concentrated in exons 7 and 8 compared to previous reports from Western countries. Six mutations (c.111dupT/p.S38Ffs(*)79, c.225_226insT/p.T76Yfs(*)41, c.383_398del16/p.S128Tfs(*)52, c.746dupT/p.H250Afs(*)20, c.1150G>T/p.E384(*), and c.1508G>A/p.G503N) were newly found in the present study. Of interest, four patients (15%) showed unusual initial presentations and three patients were diagnosed incidentally at the general medical checkup. We also found three distinct sites in exon 2 of MENIN were significantly hypomethylated in the MEN1 parathyroid tumors, comparing correspondent blood samples.

CONCLUSION

We also have found a lack of genotype/phenotype correlation in Korean MEN1 patients. There were not a few unusual initial manifestations in MEN1 patients, thus, genetic testing for the MENIN germline mutations can provide important information for the better prognosis. Further studies are warranted to investigate altered DNA methylations in the MENIN gene involved in tumorigenesis.

Inherited disorders of calcium and phosphate metabolism

PURPOSE OF REVIEW

Inherited disorders of calcium and phosphate homeostasis have variable presentation and can cause significant morbidity. An understanding of the mode of inheritance and pathophysiology of these conditions will help in the diagnosis and early institution of therapy.

RECENT FINDINGS

Identification of genetic mutations in humans and animal models has advanced our understanding of many inherited disorders of calcium and phosphate regulation. Identification of mutations of calcium-sensing receptor has improved our understanding of hypocalcemic and hypercalcemic conditions. Mutations of Fgf23, Klotho and phosphate transporter genes have been identified to cause disorders of phosphate metabolism.

SUMMARY

Calcium and phosphate homeostasis is tightly regulated in a narrow range due to their vital role in many biological processes. Inherited disorders of calcium and phosphate metabolism though uncommon can have severe morbidity. Genetic counseling of the affected families is an important part of the follow-up of these patients.

RET codon 618 mutations in Saudi families with multiple endocrine neoplasia Type 2A and familial medullary thyroid carcinoma

BACKGROUND AND OBJECTIVES

Certain diseases such as multiple endocrine neoplasia (MEN) 2A, MEN 2B, familial and sporadic medullary thyroid carcinoma (MTC) and renal dysgenesis are related to abnormalities of the RET protein. Our aim was to evaluate the frequency of RET mutation in 10 Saudi families with MEN type 2A and familial MTC.

DESIGN AND SETTING

A cross-sectional prospective study of patients followed up at King Abdulaziz University Hospital and King Abdulaziz Medical City, Jeddah, between March 2001 and March 2011.

PATIENTS AND METHODS

Genomic DNA was isolated from peripheral blood leukocytes of all subjects by standard procedures. Exons 10, 11, 13, 14 and 16 of the RET proto-oncogene were analyzed by single-strand conformation polymorphism, direct DNA sequencing and/or restriction enzyme analysis.

RESULTS

We screened 79 subjects for the RET mutation. Of which 43 subjects had hereditary MTC were en.rolled in this study. MEN type 2A was identified in 25 subjects; MTC was diagnosed in all 25 subjects (100%), pheochromocytoma in 13 subjects (52%) and hyperparathyroidism in 4 subjects (16%). The most frequent genotype in patients with MEN 2A syndrome was a codon 618 mutation (46.6%), followed by a codon 634 mutation (44.2%). Among the 5 families with MEN 2A, 3 had a mutation at codon 634, whereas 2 had a mutation at codon 618.

CONCLUSION

The most frequent RET proto-oncogene mutation in our series was in codon 618 (exon 10).

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.

Hypercalcitoninemia is not pathognomonic of medullary thyroid carcinoma

Hypercalcitoninemia has frequently been reported as a marker for medullary thyroid carcinoma. Currently, calcitonin measurements are mostly useful in the evaluation of tumor size and progression, and as an index of biochemical improvement of medullary thyroid carcinomas. Although measurement of calcitonin is a highly sensitive method for the detection of medullary thyroid carcinoma, it presents a low specificity for this tumor. Several physiologic and pathologic conditions other than medullary thyroid carcinoma have been associated with increased levels of calcitonin. Several cases of thyroid nodules associated with increased values of calcitonin are not medullary thyroid carcinomas, but rather are related to other conditions, such as hypercalcemias, hypergastrinemias, neuroendocrine tumors, renal insufficiency, papillary and follicular thyroid carcinomas, and goiter. Furthermore, prolonged treatment with omeprazole (>2-4 months), beta-blockers, glucocorticoids and potential secretagogues, have been associated with hypercalcitoninemia. An association between calcitonin levels and chronic auto-immune thyroiditis remains controversial. Patients with calcitonin levels >100 pg/mL have a high risk for medullary thyroid carcinoma (approximately 90%-100%), whereas patients with values from 10 to 100 pg/mL (normal values: <8.5 pg/mL for men, <5.0 pg/mL for women; immunochemiluminometric assay) have a <25% risk for medullary thyroid carcinoma.In multiple endocrine neoplasia type 2 (MEN2), RET mutation analysis is the gold-standard for the recommendation of total preventive thyroidectomy to relatives at risk of harboring a germline RET mutation (50%). False-positive calcitonin results within MEN2 families have led to incorrect indications of preventive total thyroidectomy to RET mutation negative relatives. In this review, we focus on the differential diagnosis of hypercalcitoninemia, underlining its importance for the avoidance of misdiagnosis of medullary thyroid carcinoma and consequent incorrect recommendation for thyroid surgery.

Clinical Use of Laboratory Tests for the Identification of Secondary Forms of Arterial Hypertension

The prevalence of secondary hypertension can be underestimated if appropriate tests are not performed. The importance of selecting patients with a high pre-test probability of secondary forms of hypertension is first discussed. The laboratory tests currently used for seeking a cause of hypertension are critically reviewed, with emphasis on their operative features and limitations. Strategies to identify primary aldosteronism, the most frequent form of secondary hypertension, and to determine its unilateral or bilateral causes are described. Treatment entails adrenalectomy in unilateral forms, and mineralocorticoid receptor blockade in bilateral forms. Renovascular hypertension is also a common, curable form of hypertension, that should be identified as early as possible to avoid the onset of cardiovascular target organ damage. The tests for its confirmation or exclusion are discussed. The various tests available for the diagnosis of pheochromocytoma, which is much rarer than the above but extremely important to identify, are also described, with emphasis on recent developments in genetic testing. Finally, the tests for diagnosing some rarer monogenic forms and other renal and endocrine causes of arterial hypertension are explored.

Multiple endocrine neoplasia

MEN1 and MEN2 are autosomal dominant cancer syndromes with the potential for considerable morbidity and mortality. Better understanding of the molecular pathogenesis in MEN1 and MEN2 has fostered the development of specific DNA screening. Knowing the genetic status of patients is valuable for making decisions regarding surveillance and interventions, such as prophylactic thyroidectomy for medullary thyroid cancer. Identifying new RET pathways has provided molecular targets for therapies that currently are being tested in clinical trials for locally advanced, metastatic, and recurrent medullary thyroid cancer.

Chronic diarrhea and facial dysmorphism in children--a clue to men 2B syndrome: a case report

Medullary thyroid cancer (MTC) is a highly malignant tumor of the thyroid gland in children, rarely diagnosed and treated by pediatric oncologists. The authors describe a 9-year-old male who presented with facial dysmorphism and history of chronic diarrhea before being diagnosed with advanced MTC. Familiarity with its clinical variants, associated RET protooncogene mutation and its clinical implication, can lead to early identification of this aggressive tumor. To date, surgery remains the only definitive therapy, with continuing dismal prognosis in metastatic disease. However, evolving newer therapeutic strategies like tyrosine kinase inhibitors and pretargeted radioimmunotherapy (pRAIT) may provide hope to children with this aggressive tumor.

Neurofibroma de tireóide em uma paciente com neurofibromatose tipo 1

A neurofibromatose tipo 1 (NF1), também conhecida como doença de von Recklinghausen, é uma doença autossômica dominante com alto grau de variabilidade da expressão clínica, comumente envolvida na formação de tumorações na maioria das vezes de origem benigna, localizadas principalmente na região da cabeça e do pescoço, sendo a tireóide acometida raramente. Porém existe na literatura a associação com carcinoma medular da tireóide (CMT), necessitando sempre sua exclusão. Relatamos o caso de uma paciente com NF1, com um nódulo de tireóide não-funcionante e sintomas obstrutivos. Foi realizada ressecção cirúrgica da lesão, com achados histopatológicos compatíveis com neurofibroma em tecido tireoidiano. A importância desse caso deve-se não só à raridade dessa apresentação da NF1, mas também à possibilidade de associação desta com CMT, tumor agressivo com possibilidade de cura pela ressecção cirúrgica.

Screening of RET gene mutations in multiple endocrine neoplasia type-2 using Conformation Sensitive Gel Electrophoresis (CSGE)

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited tumor syndrome caused by RET proto-oncogene germline mutations (RET). Here we tested the Conformation Sensitive Gel Electrophoresis (CSGE) as a screening method for RET hot-spot mutations. Seven MEN2 families were studied by direct sequencing analysis, CSGE and Single Strand Conformational Polymorphism (SSCP). Using CSGE/SSCP, we were able to detect four out of five types of RET mutations verified by sequencing analysis: Cys620Arg, Cys634Arg, Cys634Tyr, and Met918Thr, furthermore a missense substitution at codon 648 (Val648Ile). RET polymorphisms 691 and 769 were also verified. Data obtained using CSGE/SSCP were fully concordant. We conclude that CSGE showed to be a sensitive, fast, low-cost, and simple procedure to detect RET mutations in codons which are reported as the most prevalent RET variants (~ 95%) in large MEN2 series. As to the Val804Met mutation, this method still needs to be optimized.

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.

Medullary Thyroid Carcinoma

Medullary thyroid carcinoma is a neuroendocrine tumor derived from the C cells of the thyroid gland and accounts for approximately 5% of all thyroid carcinomas. Approximately 30% of the cases are associated with an autosomal dominant syndrome called multiple endocrine neoplasia type 2, and the identification of these individuals is important because affected family members may benefit from an early diagnosis. The treatment of this disease is predominantly surgical, and the impact of radiotherapy and chemotherapy is limited. The identification of the associated molecular events has lead to the development of specific molecular targeted agents that may change the way this disease is treated in the near future.

[Genetic screening of multiple endocrine neoplasia type 2: experience of the USP Endocrine Genetics Unit]

Multiple endocrine neoplasia type 2 (MEN-2) is an inherited tumor syndrome that includes medullary thyroid carcinoma (MTC), primary hyperparathyroidism, pheochromocytoma and other non-endocrine diseases. Since the first RET missense mutations in association with MEN-2 were identified, RET mutation analysis had a great impact in the clinical management of MEN-2, such as in early diagnosis and treatment of MTC. Presently, early total thyroidectomy provides real cure of MTC for cases in which molecular diagnosis has been performed at early ages. After RET mutation identification, family members should be screened for this mutation by using methods as DGGE, SSCP, restriction enzyme, genetic sequencing or mini-sequencing. In this paper, we briefly review our experience with the direct RET gene sequencing and DGGE approaches. In 50 typical MEN-2 patients analyzed using both methods, we found no false results suggesting that DGGE is a reliable screening method for RET proto-oncogene mutation analysis.

[Multiple endocrine neoplasia type 1 (MEN 1): clinical, biochemical and molecular diagnosis and treatment of the associated disturbances]

Multiple endocrine neoplasia (MEN) syndromes include types 1 (MEN 1) and 2 (MEN 2), von Hippel-Lindau syndrome, neurofibromatosis type 1 and Carney complex. These are complex genetic syndromes caused by activation or inactivation of different types of genes known to be involved in the regulation of cell proliferation. In this review we will discuss the clinical manifestations and management of the MEN 1 syndrome as well as the genetic screening of potential MEN 1 gene carriers. MEN 1 is a hereditary syndrome, transmitted in an autosomic dominant fashion and caused by an inactivating mutation of the MEN 1 gene, characterized by the development of primary hyperparathyroidism, islet cell tumors and pituitary adenomas. In addition, these patients can present with cutaneous manifestations such as angiofibromas and collagenomas, and can develop other neoplastic manifestations including carcinoids, thyroid tumors, adrenal adenomas, lipomas, pheochromocytomas and meningiomas. The MEN 1 gene encodes a peptide which is a tumor suppressor gene called menin. Several studies have demonstrated its importance in regulation of cell proliferation and have confirmed its role in the pathogenesis of the MEN 1 syndrome. The discovery of the MEN 1 gene and the genetic analysis of MEN 1 patients have resulted in earlier diagnosis and treatment of asymptomatic carriers which can potentially result in a longer survival of these patients. Further investigation of the function and signaling pathways of the menin protein will hopefully offer therapeutic alternatives to patients with malignant progression of MEN 1-related tumors and also result in improved survival.

Increased incidence of medullary thyroid carcinoma in patients treated for Hirschsprung's disease

BACKGROUND/PURPOSE

Mutations of the RET proto-oncogene are responsible for the development of inherited multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma (MTC). RET mutations are encountered in patients with Hirschsprung's disease (HD). We hypothesized that the incidence of MTC is increased in patients with HD.

METHODS

Patients treated for HD at the Children's Hospital, University of Helsinki, during 1939 and 1986 were surveyed for cancer using the population-based countrywide Finnish Cancer Registry from 1967 to 2000. The number of observed cancer cases and that of person-years at risk were counted. The expected number of cancer cases was extrapolated from national cancer incidence rates. To calculate the standardized incidence ratios (SIRs), the observed number of cancer cases was divided by the expected number of cancer cases.

RESULTS

One hundred fifty-six patients (132 males) with HD were identified. The mean length of patient follow-up was 30.9 years. Seven cases of cancer were observed (SIR, 3.5; 95% CI, 1.4-7.3). Two patients developed MTC (SIR, 550; 95% CI, 67-2000). The cases of MTC occurred in male patients at the ages of 34 and 37 years. No patient developed pheochromocytoma.

CONCLUSIONS

In this study, we report for the first time an increased risk of MTC occurring in patients treated for HD. The increased risk may be attributed to mutations of the RET proto-oncogene shared by MTC and HD. These findings warrant further studies concerning screening for MTC-type RET mutations in patients with HD.

Hyperparathyroidism and multiple endocrine neoplasia

Multiple endocrine neoplasia (MEN) syndromes comprise the group of heritable endocrinopathies, MEN 1, MEN 2A, and MEN 2B. Primary hyperparathyroidism caused by multiglandular involvement is usually the initial manifestation in MEN 1, occurring in more than 90% of patients. In patients with MEN 2A, hyperparathyroidism develops less commonly and is usually milder than in MEN 1. Advances in genetics and molecular biology aid in confirming the diagnosis and screening relatives who are carriers or at risk for the disease. Surgery plays an important role in the management of hyperparathyroidism in both MEN 1 and MEN 2A,although the timing and extent of surgery are areas of controversy.Long-term follow-up reveals a high rate of recurrent hyperparathyroidism in MEN 1 despite surgical intervention.

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 germ-line point mutation in RET exon 8 (Gly(533)Cys) in a large kindred with familial medullary thyroid carcinoma

Familial medullary thyroid carcinoma is related to germ-line mutations in the RET oncogene, mainly in cysteine codon 10 or 11, whereas noncysteine mutations in codons 13-15 are rare. We now report a new missense point mutation in exon 8 of the RET gene (1597G-->T) corresponding to a Gly(533)Cys substitution in the cysteine-rich domain of RET protein in 76 patients from a 6-generation Brazilian family with 229 subjects, with ascendants from Spain. It is likely that the mutation causes familial medullary thyroid carcinoma (FMTC), because no other mutation was found in RET, the mutation cosegregates with medullary thyroid carcinoma (MTC) or C cell hyperplasia (CCH) in patients subjected to surgery, and family members without the mutation are clinically unaffected. The histological analysis of 35 cases submitted to thyroidectomy revealed that 21 patients had MTC after the age of 40 yr and 8 before the age of 40 yr, 4 presented MTC or CCH before the age of 18 yr, 2 died due to MTC at the age of 53 and 60 yr, and CCH was found in a 5-yr-old child, suggesting a clinical heterogeneity. To improve the diagnosis of FMTC, analysis of exon 8 of RET should be considered in families with no identified classical RET mutations.

Pheochromocytoma: state-of-the-art and future prospects

This review provides current understanding of the pathophysiology of pheochromocytoma and the wide range of associated clinical manifestations that have led to earlier recognition of the disease. In addition, it reviews optimal screening methods and localization techniques that have enhanced the clinician's ability to make the diagnosis with greater certainty. This article will also discuss alternative antihypertensive regimens and innovative anesthetic and surgical procedures that have made successful management more promising than ever before. Areas requiring further development include additional clinical experience with the measurement of plasma metanephrines that have been shown to have high sensitivity and specificity in the diagnosis of sporadic and familial pheochromocytoma, optimizing cost effectiveness of diagnostic imaging, improving the ability to predict and treat malignant pheochromocytoma, and elucidating not only the surgical approach but, perhaps with rapid advances in molecular genetics, ways of preventing familial pheochromocytoma.

Von Hippel-Lindau disease

Von Hippel-Lindau (VHL) disease is an uncommon, autosomal dominant hereditary multitumor syndrome caused by germline alterations of the VHL gene, which has been cloned recently and identified as a tumor suppressor gene. The major lesions in VHL disease include hemangioblastomas in the central nervous system and retina, clear cell renal cell carcinomas, pheochromocytomas, pancreatic tumors, epididymal cystadenomas, endolymphatic sac tumors, carcinoid tumors, and multiple cysts of the kidney, pancreas, and epididymis. Compared with sporadic ones, the tumors in VHL disease develop at an earlier age and often multifocally. Histologic features of VHL tumors are characterized by their high degree of vascularization and the presence of a clear cell component. Hypervascularization is induced by overexpression of vascular endothelial growth factor (VEGF), and because the principal function of VHL protein is the negative regulation of hypoxia-inducible mRNAs including VEGF mRNA, inactivation of VHL gene plays critical roles in angiogenesis of the VHL tumors. In addition, since VHL protein is also required for the down-regulation of transcription activity of certain genes for the cell growth and cell cycle, inactivation of VHL gene may contribute to tumorigenesis of the VHL tumors. A significant difference in the frequency of types of VHL gene mutation has been noted among the affected families, known as the genotype-phenotype correlations.

Medullary thyroid cancer

Medullary thyroid cancer is a rare neoplasm that arises from the parafollicular C cells. It occurs in a sporadic form, or less commonly as a hereditary form, as part of multiple endocrine neoplasia syndromes types 2A and 2B. The RET proto-oncogene is currently the primary factor that is implicated in the hereditary forms of this neoplasm. The knowledge about the genetic makeup of the neoplasm impacts upon management as it allows for screening, early detection, and prophylactic treatment. Surgery is the main modality that offers a cure. This entails a total thyroidectomy and vigilant management and surveillance of the neck. Prognosis of patients with MTC is variable, but the more constant factors that affect it are the stage of disease and the age of the patient. The emerging molecular genetic understanding of this malignancy will provide the foundation for prognostic and therapeutic decision-making in the future. Interdisciplinary management by surgeons, endocrinologists, pathologists, radiotherapists, radiologists, and medical oncologists should be sought.

Non-cancerous ophthalmic clues to non-ocular cancer

This survey reviews selected medical disorders in which the ophthalmologist has a unique opportunity of anticipating the existence of asymptomatic, life-threatening disease simply by recognizing that certain benign conditions involving the eye or adnexa represent clues to occult non-ocular cancer and other neoplasias. Having knowledge that these clues are associated with specific types of neoplasia, the ophthalmologist can then initiate a goal-directed oncologic investigation designed to identify the underlying neoplasm with the hope of providing potentially life-saving therapy. The survey is organized to feature each clue separately. The clinical characteristics of the clue are described and illustrated with color photographs when possible. A discussion reviews associated malignancies and other important medical features. The survey begins with clues expressed anteriorly in the lids, progressively reviewing those clues located more posteriorly, concluding with clues involving the retinal pigment epithelium and choroid.

Tumorigênese Molecular Tiroideana: Implicações Para a Prática Médica

Esta revisão apresenta aspectos de utilidade prática da tumorigênese tiroideana. O mais importante é a possibilidade de se fazer o diagnóstico genético precoce dos indivíduos portadores de mutações do gene RET em famílias com carcinoma medular de tiróide e neoplasia endócrina múltipla tipo 2. Além disso, discutem-se dados relativos à patogênese molecular dos carcinomas diferenciados da tiróide, relacionados aos rearranjos entre RET e outros genes no caso do carcinoma papilífero (RET/PTC) e entre PAX-8 e PPARg1 no carcinoma folicular da tiróide. A seguir, analisam-se as mutações que causam ganho de função no receptor de TSH, causadoras dos nódulos autônomos. Finalmente, apresenta-se o emprego do RNA mensageiro da tiroglobulina no seguimento de pacientes com câncer de tiróide.

Thyroid C-cell hyperplasia in an adolescent with neurofibromatosis type 1

BACKGROUND

Subjects with neurofibromatosis type 1 (NF1) show an increased risk of endocrine tumors, especially pheochromocytoma, whereas thyroid C-cell hyperplasia (CCH) and medullary thyroid carcinoma (MTC) are very rare events described only in adult patients.

METHOD

A case of CCH diagnosed in a 14-year-old girl affected with NF1 is reported. Calcitonin serum level after pentagastin was elevated (286 pg/ml). Genetic testing was performed in order to rule out mutations in the RET proto-oncogene.

RESULT

No germline mutation previously reported in MEN2 was detected. Multifocal and bilateral CCH was demonstrated by immunohistochemistry.

CONCLUSION

It is suggested that in such a genetic background of high risk for malignancy, CCH could be considered as an extremely rare condition likely preceding MTC.

Clinical genetics of multiple endocrine neoplasias, Carney complex and related syndromes

The list of multiple endocrine neoplasias (MENs) that have been molecularly elucidated is growing with the most recent addition of Carney complex. MEN type 1 (MEN 1), which affects primarily the pituitary, pancreas, and parathyroid glands, is caused by mutations in the menin gene. MEN type 2 (MEN 2) syndromes, MEN 2A and MEN 2B that affect mainly the thyroid and parathyroid glands and the adrenal medulla, and familial medullary thyroid carcinoma (FMTC), are caused by mutations in the REToncogene. Finally, Carney complex, which affects the adrenal cortex, the pituitary and thyroid glands, and the gonads, is caused by mutations in the gene that codes for regulatory subunit type 1A of protein kinase A (PKA) (PRKAR1A) in at least half of the known patients. Molecular defects have also been identified in syndromes related to the MENs, like Peutz-Jeghers syndrome (PJS) (the STK11/LKB1 gene), and Cowden (CD; the PTEN gene) and von Hippel-Lindau disease (VHLD; the VHL gene). Although recognition of these syndromes at a young age generally improves prognosis, the need for molecular testing in the diagnostic evaluation of the MENs is less clear. This review presents the newest information on the clinical and molecular genetics of the MENs (MEN 1, MEN 2, and Carney complex), including recommendations for genetic screening, and discusses briefly the related syndromes PJS, CD and VHLD.