Should Routine Analysis of the MEN1 Gene be Performed in all Patients with Primary Hyperparathyroidism Under 40 Years of Age?

[Predicting the presence of MEN1 gene mutation based on the clinical phenotype of patients with primary hyperparathyroidism]

BACKGROUND

Timely referral of patients for genetic testing to rule out MEN1-associated primary PHPT is important factor in determining treatment strategy and prognosis. In the context of the limited availability of genetic testing, the search for clinical markers indicative of MEN1 gene mutations remains an extremely relevant task.

AIM

To determine the diagnostic value of clinical features of primary PHPT in young patients for predicting the presence of MEN1 gene mutations.

MATERIALS AND METHODS

A single-center, prospective study was conducted at the Endocrinology Research Centre, involving 273 patients with PHPT in the period 2015-2022. Based on the results of genetic and laboratory tests, patients were divided into three groups: those with MEN1 gene mutations (MEN+ group, n=71), those without MEN1 gene mutations - isolated sporadic PHPT (MEN- group, n=158), and patients with PHPT and associated endocrine gland disorders - MEN-1 syndrome phenocopies (PHEN group, n=32). Subgroups of patients younger than 40 years of age were also identified. Comparative analysis was performed among the independent groups and subgroups, and logistic regression analysis was used to develop a mathematical model for predicting the probability of the presence of MEN1 gene mutation.

RESULTS

Patients in the MEN+ and MEN- groups were comparable by gender and age at manifestation, as well as calcium-phosphorus metabolism parameters and PHPT complications. In the PHEN group, PHPT manifested at older age compared to the other groups (p<0.001 for all), with lower total calcium levels and a trend toward lower iPTH concentrations. The MEN+ group had a significantly higher frequency of multiglandular parathyroid (PG) involvement, PHPT recurrence, and positive family history compared to the MEN- and PHEN groups. Histologically, adenomas predominated in the PHEN and MEN- groups (92% and 94%, respectively), whereas hyperplasia of PGs were more common in the MEN+ group (49%). None of the PHEN patients had all three «classic» components of the MEN-1 syndrome, and the clinical course of PHPT was similar to that of the MEN- group. These differences were also observed in the subgroups of patients younger than 40 years, which formed the basis for the development of a mathematical model. The logistic regression equation for predicting the probability of the presence of the MEN1 gene mutation included eight predictors, with a diagnostic sensitivity of 96% and specificity of 98%.

CONCLUSION

Based on the analysis performed, eight hereditary predictors of PHPT within the MEN-1 syndrome were identified. A mathematical model was developed to predict the presence of the MEN1 gene mutation in patients, which demonstrated high classification performance on the training dataset. Further refinement of the model will help improve the quality of medical care for patients with PHPT.

A contemporary clinical approach to genetic testing for heritable hyperparathyroidism syndromes

PURPOSE

The improved access and affordability of next generation sequencing has facilitated the clinical use of gene panel testing to test concurrently patients for multiple heritable hyperparathyroidism syndromes. However, there is little guidance as to which patients should be selected for gene panel testing and which genes should be included in such panels. In this review, we provide a practical approach to considering, interpreting and managing genetic testing for familial primary hyperparathyroidism (PHPT) syndromes and familial hypocalciuric hypercalcaemia (FHH) in patients with PTH-dependent hypercalcaemia. We discuss known genes implicated in PHPT and FHH, testing criteria and yields, pre-test counselling, laboratory considerations, and post-test management.

METHODS

In addition to reviewing the literature, we conducted audits of local genetic testing data to examine the real-world yield of genetic testing in patients with PTH-dependent hypercalcaemia.

RESULTS

Our local audits revealed a positive genetic testing rate of 15-26% in patients with suspected hyperparathyroidism syndromes.

CONCLUSION

Based on the particular testing criteria met, affected patients should be tested for variants in the genes currently implicated in PHPT (MEN1, CDC73, RET, CDKN1B, GCM2, CASR) and/or FHH (CASR, GNA11, AP2S1). Patients should be provided with pre- and post-test counselling, including consideration of potential implications for family members.

Analyzing Genetic Differences Between Sporadic Primary and Secondary/Tertiary Hyperparathyroidism by Targeted Next-Generation Panel Sequencing

Secondary hyperparathyroidism (SHPT) is characterized by excessive serum parathyroid hormone levels in response to decreasing kidney function, and tertiary hyperparathyroidism (THPT) is often the result of a long-standing SHPT. To date, several genes have been associated with the pathogenesis of primary hyperparathyroidism (PHPT). However, the molecular genetic mechanisms of uremic hyperparathyroidism (HPT) remain uncharacterized. To elucidate the differences in genetic alterations between PHPT and SHPT/THPT, the targeted next-generation sequencing of genes associated with HPT was performed using DNA extracted from parathyroid tissues. As a result, 26 variants in 19 PHPT or SHPT/THPT appeared as candidate pathogenic mutations, which corresponded to 9 (35%) nonsense, 8 (31%) frameshift, 6 (23%) missense, and 3 (11%) splice site mutations. The MEN1 (23%, 6/26), ASXL3 (15%, 4/26), EZH2 (12%, 3/26), and MTOR (8%, 2/26) genes were frequently mutated. Sixteen of 25 patients with PHPT (64%) had one or more mutations, whereas 3 (21%) of 21 patients with SHPT/THPT had only 1 mutation (p = 0.001). Sixteen of 28 patients (57%) with parathyroid adenoma (PA) had one or more mutations, whereas 3 of 18 patients (17%) with parathyroid hyperplasia (PH) had just one mutation (p = 0.003). Known driver mutations associated with parathyroid tumorigenesis such as CCND1/PRAD1, CDC73/HRPT2, and MEN1 were identified only in PA (44%, 7/16 with mutations). Our results suggest that molecular genetic abnormalities in SHPT/THPT are distinct from those in PHPT. These findings may help in analyzing the molecular pathogenesis underlying uremic HPT development.

Multiple endocrine neoplasia type 2: A reveiw

Multiple endocrine neoplasias are rare hereditary syndromes some of them with malignant potential. Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant hereditary cancer syndrome due to germline variants in the REarranged during Transfection (RET) proto-oncogene. There are two distinct clinical entities: MEN 2A and MEN 2B. MEN 2A is associated with medullary thyroid carcinoma (MTC), phaeochromocytoma, primary hyperparathyroidism, cutaneous lichen amyloidosis and Hirschprung's disease and MEN 2B with MTC, phaeochromocytoma, ganglioneuromatosis of the aerodigestive tract, musculoskeletal and ophthalmologic abnormalities. Germline RET variants causing MEN 2 result in gain-of-function; since the discovery of the genetic variants a thorough search for genotype-phenotype associations began in order to understand the high variability both between families and within family members. These studies have successfully led to improved risk classification of prognosis in relation to the genotype, thus improving the management of the patients by thorough genetic counseling. The present review summarizes the recent developments in the knowledge of these hereditary syndromes as well as the impact on clinical management, including genetic counseling, of both individual patients and families. It furthermore points to future directions of research for better clarification of timing of treatments of the various manifestations of the syndromes in order to improve survival and morbidity in these patients.

Clinical aspects of multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is a rare syndrome characterized by the co-occurrence of primary hyperparathyroidism, duodenopancreatic neuroendocrine tumours (NETs) and/or pituitary adenomas. MEN1 can predispose patients to other endocrine and non-endocrine tumours, such as cutaneous tumours, central nervous system tumours and breast cancer. Endocrine tumours in patients with MEN1 differ from sporadic tumours in that they have a younger age at onset, present as multiple tumours in the same organ and have a different clinical course. Therefore, patients with overt MEN1 and those who carry a MEN1 mutation should be offered tailored biochemical and imaging screening to detect tumours and evaluate their progression over time. Fortunately, over the past 10 years, knowledge about the clinical phenotype of these tumours has markedly progressed, thanks to the implementation of national registries, particularly in France and the Netherlands. This Review provides an update on the clinical management of MEN1-related tumours. Epidemiology, the clinical picture, diagnostic work-up and the main lines of treatment for MEN1-related tumours are summarized. Controversial therapeutic aspects and issues that still need to be addressed are also discussed. Moreover, special attention is given to MEN1 manifestations in children and adolescents.

Familial Hyperparathyroidism

Regulation of the serum calcium level in humans is achieved by the endocrine action of parathyroid glands working in concert with vitamin D and a set of critical target cells and tissues including osteoblasts, osteoclasts, the renal tubules, and the small intestine. The parathyroid glands, small highly vascularized endocrine organs located behind the thyroid gland, secrete parathyroid hormone (PTH) into the systemic circulation as is needed to keep the serum free calcium concentration within a tight physiologic range. Primary hyperparathyroidism (HPT), a disorder of mineral metabolism usually associated with abnormally elevated serum calcium, results from the uncontrolled release of PTH from one or several abnormal parathyroid glands. Although in the vast majority of cases HPT is a sporadic disease, it can also present as a manifestation of a familial syndrome. Many benign and malignant sporadic parathyroid neoplasms are caused by loss-of-function mutations in tumor suppressor genes that were initially identified by the study of genomic DNA from patients who developed HPT as a manifestation of an inherited syndrome. Somatic and inherited mutations in certain proto-oncogenes can also result in the development of parathyroid tumors. The clinical and genetic investigation of familial HPT in kindreds found to lack germline variants in the already known HPT-predisposition genes represents a promising future direction for the discovery of novel genes relevant to parathyroid tumor development.

[Adenoma of the parathyroid gland in a young woman with chronic kidney disease: primary or tertiary hyperparathyroidism?]

Clinical observation of a young woman with chronic kidney disease IV stage and hyperparathyroidism is presented. Ultrasound and99mTc-sestamibi scintigraphy of the anterior surface of the neck visualized a tumor of the left upper parathyroid gland. In a histological examination of distant education was diagnosed a solid parathyroid adenoma. The difficulty of differential diagnosis between primary and secondary/tertiary hyperparathyroidism in chronic kidney disease is discussed.

[Hereditary syndromal and nonsyndromal forms of primary hyperparathyroidism]

Primary hyperparathyroidism is a common disorder of mineral homeostasis, characterized by overproduction of parathyroid hormone and upper normal or elevated calcium levels due to hyperplasia or a tumor of parathyroid gland. 90&minus;95% of cases of primary hyperparathyroidism are sporadic, while hereditary genetic forms occur in 5&ndash;10% of all cases. Primary hyperparathyroidism as the component of hereditary syndromes can present in various clinical forms (asymptomatic, symptomatic), can be associated with other endocrine or non-endocrine diseases, and require special approaches to treatment. Given that primary hyperparathyroidism is one of the most common components of these syndromes, it can be used as an important diagnostic tool in identifying affected families. This review is devoted to modern ideas about the clinical course and genetic characteristics of hereditary variants of primary hyperparathyroidism and the diagnostic and treatment algorithms recommended today. The review considers primary hyperparathyroidism as a component of hereditary syndromes including multiple endocrine neoplasias types 1, 2A and 4 and syndrome of hyperparathyroidism with a jaw tumor. Also non-syndromic hereditary forms are descripted, such as familial isolated hyperparathyroidism, familial hypocalciuric hypercalcemia, and severe neonatal primary hyperparathyroidism.

Primary hyperparathyroidism as first manifestation in multiple endocrine neoplasia type 2A: an international multicenter study

OBJECTIVE

Multiple endocrine neoplasia type 2A (MEN 2A) is a rare syndrome caused by RET germline mutations and has been associated with primary hyperparathyroidism (PHPT) in up to 30% of cases. Recommendations on RET screening in patients with apparently sporadic PHPT are unclear. We aimed to estimate the prevalence of cases presenting with PHPT as first manifestation among MEN 2A index cases and to characterize the former cases.

DESIGN AND METHODS

An international retrospective multicenter study of 1085 MEN 2A index cases. Experts from MEN 2 centers all over the world were invited to participate. A total of 19 centers in 17 different countries provided registry data of index cases followed from 1974 to 2017.

RESULTS

Ten cases presented with PHPT as their first manifestation of MEN 2A, yielding a prevalence of 0.9% (95% CI: 0.4-1.6). 9/10 cases were diagnosed with medullary thyroid carcinoma (MTC) in relation to parathyroid surgery and 1/10 was diagnosed 15 years after parathyroid surgery. 7/9 cases with full TNM data were node-positive at MTC diagnosis.

CONCLUSIONS

Our data suggest that the prevalence of MEN 2A index cases that present with PHPT as their first manifestation is very low. The majority of index cases presenting with PHPT as first manifestation have synchronous MTC and are often node-positive. Thus, our observations suggest that not performing RET mutation analysis in patients with apparently sporadic PHPT would result in an extremely low false-negative rate, if no other MEN 2A component, specifically MTC, are found during work-up or resection of PHPT.

Hypercalcaemia during pregnancy: Review of maternal and fetal complications, investigations, and management

Introduction

Asymptomatic mild primary hyperparathyroidism is increasingly being identified during pregnancy. Recent studies have demonstrated inconsistent findings with regard to pregnancy complications and the need for surgical intervention during pregnancy.

Method

A retrospective audit of outcomes of pregnancies complicated by hypercalcaemia over a 15-year period was performed.

Results

Twenty-nine pregnancies to 26 women with hypercalcaemia were identified, corresponding to 37 cases per 100,000 deliveries. Hypercalcaemia was due to primary hyperparathyroidism in 90% of cases, with mean serum calcium of 2.89 mmol/l and mean ionised calcium 1.43 mmol/l. Four women underwent successful neck exploration during pregnancy. Pregnancy complications were limited to three cases of pre-eclampsia and one case of symptomatic neonatal hypoparathyroidism.

Conclusion

Close observation without surgical intervention would seem reasonable in women with mild hypercalcaemia during pregnancy.

Primary hyperparathyroidism in young patients in Russia: high frequency of hyperparathyroidism-jaw tumor syndrome

BACKGROUND

Primary hyperparathyroidism (PHPT) is a relatively rare disorder among children, adolescents and young adults. Its development at an early age is suspicious for hereditary causes, though the need for routine genetic testing remains controversial.

OBJECTIVE

To identify and describe hereditary forms of PHPT in patients with manifestation of the disease under 40 years of age.

DESIGN

We enrolled 65 patients with PHPT diagnosed before 40 years of age. Ten of them had MEN1 mutation, and PHPT in them was the first manifestation of multiple endocrine neoplasia type 1 syndrome.

METHODS

The other fifty-five patients underwent next-generation sequencing (NGS) of a custom-designed panel of genes, associated with PHPT (MEN1, CASR, CDC73, CDKN1A, CDKN1B, CDKN1C, CDKN2A, CDKN2C, CDKN2D). In cases suspicious for gross CDC73 deletions multiplex ligation-dependent probe amplification was performed.

RESULTS

NGS revealed six pathogenic or likely pathogenic germline sequence variants: four in CDC73 c.271C>T (p.Arg91*), c.496C>T (p.Gln166*), c.685A>T (p.Arg229*) and c.787C>T (p.Arg263Cys); one in CASR c.3145G>T (p.Glu1049*) and one in MEN1 c.784-9G>A. In two patients, MLPA confirmed gross CDC73 deletions. In total, 44 sporadic and 21 hereditary PHPT cases were identified. Parathyroid carcinomas and atypical parathyroid adenomas were present in 8/65 of young patients, in whom CDC73 mutations were found in 5/8.

CONCLUSIONS

Hereditary forms of PHPT can be identified in up to 1/3 of young patients with manifestation of the disease at <40 years of age. Parathyroid carcinomas or atypical parathyroid adenomas in young patients are frequently associated with CDC73 mutations.

Hereditary hyperparathyroidism--a consensus report of the European Society of Endocrine Surgeons (ESES)

BACKGROUND

Hereditary hyperparathyroidism has been reported to occur in 5-10 % of cases of primary hyperparathyroidism in the context of multiple endocrine neoplasia (MEN) types 1, 2A and 4; hyperparathyroidism-jaw tumour (HPT-JT); familial isolated hyperparathyroidism (FIHPT); familial hypocalciuric hypercalcaemia (FHH); neonatal severe hyperparathyroidism (NSHPT) and autosomal dominant moderate hyperparathyroidism (ADMH). This paper aims to review the controversies in the main genetic, clinical and pathological features and surgical management of hereditary hyperparathyroidism.

METHODS

A peer review literature analysis on hereditary hyperparathyroidism was carried out and analyzed in an evidence-based perspective. Results were discussed at the 2015 Workshop of the European Society of Endocrine Surgeons devoted to hyperparathyroidism due to multiple gland disease.

RESULTS

Literature reports scarcity of prospective randomized studies; thus, a low level of evidence may be achieved.

CONCLUSIONS

Hereditary hyperparathyroidism typically presents at an earlier age than the sporadic variants. Gene penetrance and expressivity varies. Parathyroid multiple gland involvement is common, but in some variants, it may occur metachronously often with long disease-free intervals, simulating a single-gland involvement. Bilateral neck exploration with subtotal parathyroidectomy or total parathyroidectomy + autotransplantation should be performed, especially in MEN 1, in order to decrease the persistent and recurrent hyperparathyroidism rates; in some variants (MEN 2A, HPT-JT), limited parathyroidectomy can achieve long-term normocalcemia. In FHH, surgery is contraindicated; in NSHPT, urgent total parathyroidectomy is required. In FIHPT, MEN 4 and ADMH, a tailored case-specific approach is recommended.

Operative Failure Rate and Documentation of Family History in Young Patients Undergoing Focused Parathyroidectomy for Primary Hyperparathyroidism

Primary hyperparathyroidism in multiple endocrine neoplasia type I usually affects all parathyroid glands, making focused parathyroidectomy (FP) inappropriate. The risk of previously undiagnosed multiple endocrine neoplasia type I in a younger patient with primary hyperparathyroidism is higher than in an older patient. We hypothesized that FP may lead to a higher failure rate in younger versus older patients. A retrospective review was performed of a single-institution database of patients who underwent parathyroidectomy for primary hyperparathyroidism. Routine statistical analysis was performed, including Fisher's exact test. A total of 635 patients were included. Operative failure occurred in 7/55 (13%) younger patients and 21/580 (4%) older patients ( P = 0.007). In conclusion, operative failure occurred in a statistically significantly higher percentage of younger versus older patients undergoing FP. This is partly explained by undiagnosed multiple endocrine neoplasia syndrome type I in the younger patient group. Endocrine surgeons must make every effort to preoperatively identify multiple endocrine neoplasia syndrome type I in the younger patient population.

A practice guideline from the American College of Medical Genetics and Genomics and the National Society of Genetic Counselors: referral indications for cancer predisposition assessment

DISCLAIMER

The practice guidelines of the American College of Medical Genetics and Genomics (ACMG) and the National Society of Genetic Counselors (NSGC) are developed by members of the ACMG and NSGC to assist medical geneticists, genetic counselors, and other health-care providers in making decisions about appropriate management of genetic concerns, including access to and/or delivery of services. Each practice guideline focuses on a clinical or practice-based issue and is the result of a review and analysis of current professional literature believed to be reliable. As such, information and recommendations within the ACMG and NSGC joint practice guidelines reflect the current scientific and clinical knowledge at the time of publication, are current only as of their publication date, and are subject to change without notice as advances emerge. In addition, variations in practice, which take into account the needs of the individual patient and the resources and limitations unique to the institution or type of practice, may warrant approaches, treatments, and/or procedures that differ from the recommendations outlined in this guideline. Therefore, these recommendations should not be construed as dictating an exclusive course of management, nor does the use of such recommendations guarantee a particular outcome. Genetic counseling practice guidelines are never intended to displace a health-care provider's best medical judgment based on the clinical circumstances of a particular patient or patient population. Practice guidelines are published by the ACMG or the NSGC for educational and informational purposes only, and neither the ACMG nor the NSGC "approve" or "endorse" any specific methods, practices, or sources of information.Cancer genetic consultation is an important aspect of the care of individuals at increased risk of a hereditary cancer syndrome. Yet several patient, clinician, and system-level barriers hinder identification of individuals appropriate for cancer genetics referral. Thus, the purpose of this practice guideline is to present a single set of comprehensive personal and family history criteria to facilitate identification and maximize appropriate referral of at-risk individuals for cancer genetic consultation. To develop this guideline, a literature search for hereditary cancer susceptibility syndromes was conducted using PubMed. In addition, GeneReviews and the National Comprehensive Cancer Network guidelines were reviewed when applicable. When conflicting guidelines were identified, the evidence was ranked as follows: position papers from national and professional organizations ranked highest, followed by consortium guidelines, and then peer-reviewed publications from single institutions. The criteria for cancer genetic consultation referral are provided in two formats: (i) tables that list the tumor type along with the criteria that, if met, would warrant a referral for a cancer genetic consultation and (ii) an alphabetical list of the syndromes, including a brief summary of each and the rationale for the referral criteria that were selected. Consider referral for a cancer genetic consultation if your patient or any of their first-degree relatives meet any of these referral criteria.

Two case reports of pilot percutaneous cryosurgery in familial multiple endocrine neoplasia type 1

We report 2 cases of familial multiple endocrine neoplasia type 1 syndrome (MEN 1) in related Malaysian Chinese individuals: the son had simultaneous primary lesions in the pancreatic tail, parathyroid, adrenal gland, and hypophysis, with metastatic tumors in the left lung, mediastinum and spine; his mother had simultaneous primary lesions in the pancreatic head, parathyroid, and hypophysis, with metastatic tumors in the liver, spine, ilium, chest wall, and rib. Genetic testing of the 2 patients showed the same mutation in exon 9 of MEN1 (c.1288G>T, Glu430, encoding a stop codon). The tumors with the poorest prognosis and clinical sequelae were in the pancreas of both patients, and these were treated by percutaneous cryoablation. The number of hypoglycemic episodes in the son improved for more than 120 days, and the abdominal space occupying lesion resolved in his mother.

Clinical practice guidelines for multiple endocrine neoplasia type 1 (MEN1)

OBJECTIVE

The aim was to provide guidelines for evaluation, treatment, and genetic testing for multiple endocrine neoplasia type 1 (MEN1).

PARTICIPANTS

The group, which comprised 10 experts, including physicians, surgeons, and geneticists from international centers, received no corporate funding or remuneration.

PROCESS

Guidelines were developed by reviews of peer-reviewed publications; a draft was prepared, reviewed, and rigorously revised at several stages; and agreed-upon revisions were incorporated.

CONCLUSIONS

MEN1 is an autosomal dominant disorder that is due to mutations in the tumor suppressor gene MEN1, which encodes a 610-amino acid protein, menin. Thus, the finding of MEN1 in a patient has important implications for family members because first-degree relatives have a 50% risk of developing the disease and can often be identified by MEN1 mutational analysis. MEN1 is characterized by the occurrence of parathyroid, pancreatic islet, and anterior pituitary tumors. Some patients may also develop carcinoid tumors, adrenocortical tumors, meningiomas, facial angiofibromas, collagenomas, and lipomas. Patients with MEN1 have a decreased life expectancy, and the outcomes of current treatments, which are generally similar to those for the respective tumors occurring in non-MEN1 patients, are not as successful because of multiple tumors, which may be larger, more aggressive, and resistant to treatment, and the concurrence of metastases. The prognosis for MEN1 patients might be improved by presymptomatic tumor detection and undertaking treatment specific for MEN1 tumors. Thus, it is recommended that MEN1 patients and their families should be cared for by multidisciplinary teams comprising relevant specialists with experience in the diagnosis and treatment of patients with endocrine tumors.

Role of multiple endocrine neoplasia type 1 mutational analysis in clinical practice

OBJECTIVE

To review and assess the role of MEN1 mutational analysis in clinical practice.

METHODS

Articles relevant to MEN1 mutation testing and screening were reviewed.

RESULTS

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant disorder characterized by the combined occurrence of tumors of the parathyroid glands, pancreatic islet cells, and anterior pituitary gland. MEN 1 is associated with premature mortality attributable primarily to malignant pancreatic neuroendocrine tumors and foregut carcinoids. The MEN1 gene is located on chromosome 11q13, and germline MEN1 mutations are highly penetrant and lead to tumor development in >99% of patients by the age of 45 years. Current consensus guidelines recommend an integrated program of mutational analysis of the MEN1 gene and a combination of biochemical and radiologic screening to detect the early development of tumors and thereby reduce the morbidity and mortality associated with MEN 1. Our results reveal that MEN1 mutational analysis helps to confirm the clinical diagnosis, identify asymptomatic family members who have a MEN1 mutation and require screening from an early age, and identify the 50% of family members who do not have the MEN1 mutation and can therefore have the burden of screening and anxiety regarding potential disease removed. Moreover, MEN1 mutational analysis helps to resolve diagnostic challenges due to phenocopies, which occur in 5% to 10% of families with MEN 1.

CONCLUSION

MEN1 mutational analysis facilitates clinical management and provides benefits to patients and families with MEN 1.

Application of genetic testing to define the surgical approach in a sporadic case of multiple endocrine neoplasia type 1

We report the use of a genetic test for therapeutic decision making in a case of primary hyperparathyroidism associated with Cushing's disease (CD). A 20-year-old woman was evaluated for gradual weight gain, asthenia, muscle pain, and hypertension. Biochemical and radiologic tests confirmed CD and she underwent transsphenoidal surgery. Immunohistochemistry of the microadenoma was positive for adrenocorticotropic hormone (ACTH). On follow-up, hypercalcemia with high parathyroid hormone (PTH) levels was detected, associated with nephrolithiasis and low bone mineral density in the spine and hip. Parathyroid scintigraphy showed tracer uptake in the inferior region of the left thyroid lobe, and cervical ultrasound showed a heterogeneous nodule in the same area, suggestive of a parathyroid adenoma (PA). Genetic testing detected mutation in the MEN 1 gene and total parathyroidectomy with the implantation of a fragment of one gland in the forearm was performed. Pathology showed a PA and 3 normal parathyroid glands, without hyperplasia, despite the diagnosis of MEN 1. This case illustrates the role of genetic testing in defining the therapeutic approach for sporadic MEN 1.

Primary hyperparathyroidism in patients with multiple endocrine neoplasia type 1

Primary hyperparathyroidism may occur as a part of an inherited syndrome in a combination with pancreatic endocrine tumours and/or pituitary adenoma, which is classified as Multiple Endocrine Neoplasia type 1 (MEN-1). This syndrome is caused by a germline mutation in MEN-1 gene encoding a tumour-suppressor protein, menin. Primary hyperparathyroidism is the most frequent clinical presentation of MEN-1, which usually appears in the second decade of life as an asymptomatic hypercalcemia and progresses through the next decades. The most frequent clinical presentation of MEN-1-associated primary hyperparathyroidism is bone demineralisation and recurrent kidney stones rarely followed by chronic kidney disease. The aim of this paper is to present the pathomechanism, screening procedures, diagnosis, and management of primary hyperparathyroidism in the MEN-1 syndrome. It also summarises the recent advances in the pharmacological therapy with a new group of drugs-calcimimetics.