Multiple endocrine neoplasia type 1 (MEN1): Not only inherited endocrine tumors

A novel menin gene deletional mutation in a little series of Italian patients affected by apparently sporadic multiple endocrine neoplasia type 1 syndrome

AIM

To perform a genetic screening for the multiple endocrine neoplasia type 1 (MEN1) gene mutations in patients affected by an apparently sporadic form of the disease, referred to an internal medicine unit of a large general hospital.

SUBJECTS AND METHODS

In a group of 12 consecutive patients presenting clinical features of MEN type 1 syndrome, we performed a genetic screening for germline MEN1 gene mutations, including complete sequencing of the coding region (exons 2 to 10) and multiplex ligation-dependent probe amplification analysis for large deletion detection.

RESULTS

Among these patients affected by apparently sporadic MEN type 1 syndrome, a targeted clinical history could detect indirect support for a diagnosis of familial condition only in 2 cases. The genetic screening identified pathogenic germline MEN1 gene mutations in 3 patients (25%). A previously unknown 18 base-pair deletion within exon 3, c.564_581delCAATGGGGAGCAGACAGC, resulting in loss of 6 amino acids (pAsp189_Ala194del), was found in heterozygosis in a woman affected by primary hyperparathyroidism and multifocal pancreatic neoplasia.

CONCLUSIONS

Our results underscore the importance of performing genetic testing also in apparently sporadic MEN1 patients and extend the list of molecular variants leading to inactivation of the MEN1 gene.

Are microRNAs involved in the endocrine-specific pattern of tumorigenesis in multiple endocrine neoplasia type 1?

OBJECTIVE

To provide a general background regarding current knowledge about microRNA (miRNA) involvement in endocrine functions and in multiple endocrine neoplasia type 1 (MEN 1) endocrine tumorigenesis.

METHODS

A literature search was conducted in the miRNA database for articles on the role of miRNAs in the initiation and progression of human malignant conditions, inasmuch as miRNAs show different patterns of expression in normal and neoplastic tissues. We address the potential role of miRNAs in the endocrine pancreas, the pituitary gland, and the parathyroid glands-areas where MEN 1 shows high penetrance.

RESULTS

Experimental studies have shown the involvement of miRNAs in regulation of endocrine functions, such as insulin secretion. Moreover, studies have provided evidence that dysregulation of miRNAs was responsible for endocrine carcinogenesis, including pancreatic, pituitary, and parathyroid tumors.

CONCLUSION

miRNA expression profiles may become useful biomarkers for endocrine tumor diagnostics as well as potential targets of therapeutic strategies applied to pathologic conditions such as type 2 diabetes and endocrine tumors. Future studies should investigate the molecular and cellular mechanisms of tissue selectivity in MEN 1-associated tumorigenesis, in an effort to develop an RNA-based treatment that could prevent or delay the onset of MEN 1-associated tumors.

Pituitary tumors in patients with MEN1 syndrome

We briefly review the characteristics of pituitary tumors associated with multiple endocrine neoplasia type 1. Multiple endocrine neoplasia type 1 is an autosomal-dominant disorder most commonly characterized by tumors of the pituitary, parathyroid, endocrine-gastrointestinal tract, and pancreas. A MEDLINE search for all available publications regarding multiple endocrine neoplasia type 1 and pituitary adenomas was undertaken. The prevalence of pituitary tumors in multiple endocrine neoplasia type 1 may vary from 10% to 60% depending on the studied series, and such tumors may occur as the first clinical manifestation of multiple endocrine neoplasia type 1 in 25% of sporadic and 10% of familial cases. Patients were younger and the time between initial and subsequent multiple endocrine neoplasia type 1 endocrine lesions was significantly longer when pituitary disease was the initial manifestation of multiple endocrine neoplasia type 1. Tumors were larger and more invasive and clinical manifestations related to the size of the pituitary adenoma were significantly more frequent in patients with multiple endocrine neoplasia type 1 than in subjects with non-multiple endocrine neoplasia type 1. Normalization of pituitary hypersecretion was much less frequent in patients with multiple endocrine neoplasia type 1 than in subjects with non-multiple endocrine neoplasia type 1. Pituitary tumors in patients with multiple endocrine neoplasia type 1 syndrome tend to be larger, invasive and more symptomatic, and they tend to occur in younger patients when they are the initial presentation of multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia: the Chilean experience

Multiple endocrine neoplasia (MEN) types 1 and 2 are genetic diseases that are inherited as autosomal traits. The major clinical manifestations of multiple endocrine neoplasia type 1 include the so-called "3 P's": parathyroid, pituitary, and pancreatic tumors, including gastroenteroneuroendocrine tumors. Genetic testing can be performed on patients and the potential carriers of the menin gene mutation, but the genotype-phenotype correlation in multiple endocrine neoplasia type 1 is less straightforward than multiple endocrine neoplasia type 2. Most likely, the main advantage of genetic testing in MEN1 is to exclude from further studies those who are negative for the genetic mutation if they belong to a family with a known history of MEN1. In Chile, we started with rearranged during transfection proto-oncogene genetic testing (MEN2) 15 years ago. We carried out a prophylactic total thyroidectomy to prevent medullary thyroid carcinoma in a three-year-old girl who presented with microscopic medullary thyroid carcinoma. More than 90% of the individuals who tested positive using a genetic test achieved a biochemical cure compared with only 27% of patients who receive a clinical diagnosis. Mutations are mainly located in exon 11; the most common is C634W, rather than C634R. Hypertensive crisis was the cause of death in three patients, and extensive distant metastases occurred in nine (including two patients with multiple endocrine neoplasia type 2B) of 14 patients. Earlier recognition of medullary thyroid carcinoma and the other features of the disease, especially pheochromocytoma, will improve the survival rate of patients with multiple endocrine neoplasia.

Primary hyperparathyroidism in multiple endocrine neoplasia type 1: when to perform surgery?

Primary hyperparathyroidism is a common endocrinological disorder. In rare circumstances, it is associated with familial syndromes, such as multiple endocrine neoplasia type 1. This syndrome is caused by a germline mutation in the multiple endocrine neoplasia type 1 gene encoding the tumor-suppressor protein menin. Usually, primary hyperparathyroidism is the initial clinical expression in carriers of multiple endocrine neoplasia type 1 mutations, occurring in more than 90% of patients and appearing at a young age (20-25 years). Multiple endocrine neoplasia type 1/primary hyperparathyroidism is generally accompanied by multiglandular disease, clinically manifesting with hypercalcemia, although it can remain asymptomatic for a long time and consequently not always be recognized early. Surgery is the recommended treatment. The goal of this short review is to discuss the timing of surgery in patients when primary hyperparathyroidism is associated with multiple endocrine neoplasia type 1.

Total parathyroidectomy in a large cohort of cases with hyperparathyroidism associated with multiple endocrine neoplasia type 1: experience from a single academic center

Most cases of sporadic primary hyperparathyroidism present disturbances in a single parathyroid gland and the surgery of choice is adenomectomy. Conversely, hyperparathyroidism associated with multiple endocrine neoplasia type 1 (hyperparathyroidism/multiple endocrine neoplasia type 1) is an asynchronic, asymmetrical multiglandular disease and it is surgically approached by either subtotal parathyroidectomy or total parathyroidectomy followed by parathyroid auto-implant to the forearm. In skilful hands, the efficacy of both approaches is similar and both should be complemented by prophylactic thymectomy. In a single academic center, 83 cases of hyperparathyroidism/ multiple endocrine neoplasia type 1 were operated on from 1987 to 2010 and our first surgical choice was total parathyroidectomy followed by parathyroid auto-implant to the non-dominant forearm and, since 1997, associated transcervical thymectomy to prevent thymic carcinoid. Overall, 40% of patients were given calcium replacement (mean intake 1.6 g/day) during the first months after surgery, and this fell to 28% in patients with longer follow-up. These findings indicate that several months may be needed in order to achieve a proper secretion by the parathyroid auto-implant. Hyperparathyroidism recurrence was observed in up to 15% of cases several years after the initial surgery. Thus, long-term follow-up is recommended for such cases. We conclude that, despite a tendency to subtotal parathyroidectomy worldwide, total parathyroidectomy followed by parathyroid auto-implant is a valid surgical option to treat hyperparathyroidism/multiple endocrine neoplasia type 1. Larger comparative systematic studies are needed to define the best surgical approach to hyperparathyroidism/multiple endocrine neoplasia type 1.

A rare case of an aldosterone secreting metastatic adrenocortical carcinoma and papillary thyroid carcinoma in a 31-year-old male

We report a rare synchronous presentation of adrenocortical carcinoma (ACC) and papillary thyroid carcinoma (PTC). A 31-year-old male first presented with a large left adrenal mass that was identified during the workup for refractory hypertension due to hyperaldosteronism. The mass was removed surgically with pathology showing ACC. The patient was then treated with adjuvant radiation therapy and mitotane chemotherapy. Four months post ACC resection, metastatic ACC to the right upper lung and PTC in the left lobe of the thyroid were found in surveillance imaging. He subsequently developed pulmonary, contralateral adrenal and brain metastases from his ACC. Li Fraumeni syndrome and Multiple Endocrine Neoplasia Type I (MEN I) were considered, but testing of both P53 and menin genes showed no mutation. We also performed a review of the literature and found three similar cases, however gene mutation analysis was not performed..

A novel missense mutation in the MEN1 gene in a patient with multiple endocrine neoplasia type 1

OBJECTIVE

To describe a novel germline missense mutation in exon 2 of the MEN1 gene identified in a man with multiple endocrine neoplasia type 1 (MEN 1).

METHODS

We describe the patient's clinical, laboratory, and genetic data, and we review the relevant literature.

RESULTS

A 41-year-old man with a history of primary hyperparathyroidism and left lower parathyroidectomy presented with nausea, vomiting, and hematemesis. Laboratory data revealed an elevated gastrin level. Computed tomography of the abdomen demonstrated a 3.5-cm mass in the head of pancreas. A functional study with a somatostatin receptor scan showed increased uptake in the region of the pancreatic mass. The patient's symptoms promptly improved after the Whipple procedure, although he was also noted to have a markedly elevated calcium concentration along with inappropriately elevated parathyroid hormone levels. Sestamibi scan identified a hyperfunctioning right upper parathyroid gland. His calcium level normalized after parathyroidectomy, and results from pituitary hormone studies were all normal. Genetic testing of the MEN1 gene identified a novel mutation: Arg52Gly. The Arg52Gly mutation replaces the normal arginine residue (CGC) with a glycine residue (GGC) at position 52 of the resultant menin protein. This mutation was present in family members from 3 generations.

CONCLUSIONS

We report a novel disease-causing germline missense mutation in exon 2 of the MEN1 gene in a patient with MEN 1. Nonconservative replacement of arginine, a small, neutral amino acid, with glycine, a bulky positively charged amino acid, could potentially have a deleterious effect on the menin protein.

[Familial isolated pituitary adenoma syndrome]

Familial pituitary adenomas occur in multiple endocrine neoplasia type 1, Carney complex, as well as in familial isolated pituitary adenoma syndrome. Familial isolated pituitary adenoma syndrome is an autosomal dominant disease with incomplete penetrance. Pituitary adenomas occur in familial setting but without any other specific tumors. In 20-40% of families with this syndrome, mutations have been identified in the aryl hydrocarbon receptor interacting protein gene while in the rest of the families the causative gene or genes have not been identified. Families carrying aryl hydrocarbon receptor interacting protein gene mutations have a distinct phenotype with younger age at diagnosis and a predominance of somatotroph and lactotroph adenomas. Germline mutations of the aryl hydrocarbon receptor interacting protein gene can be occasionally identified in usually young-onset seemingly sporadic cases. Genetic and clinical testing of relatives of patients with aryl hydrocarbon receptor interacting protein gene mutations can lead to earlier diagnosis and treatment at an earlier stage of the pituitary tumor.

The growing role for genetic counseling in endocrinology

PURPOSE OF REVIEW

The field of cancer genetics and genetic testing is expanding rapidly. As our understanding of the hereditary nature of endocrine tumors increases, the role of genetic counseling on the multidisciplinary endocrinology team is becoming more critical. This brief review will highlight the role of the certified genetic counselor in this setting.

RECENT FINDINGS

Genetic counseling and testing may aid in the management of the endocrine patient through early diagnosis and detection of disease, by optimizing surgical decision-making and improving overall survival. Certified genetic counselors assist the endocrinology team by eliciting a detailed pedigree, determining the appropriate genetic test to order, obtaining informed consent, interpreting complex genetic test results, providing psychosocial and family counseling, and assessing which family members are at risk. Many endocrine tumors can be caused by a variety of different genes and investment in the genetic counseling process likely increases the chance that the correct genetic test is ordered, results are interpreted accurately, and adequate informed consent and counseling is offered.

SUMMARY

The field of endocrine genetics is growing exponentially and testing will likely play an even greater role in surveillance, medical management, and surgical decision-making in the next decade. Genetic counseling both pretesting and posttesting is essential to accurate, cost-efficient care for the endocrine patient and the entire family.

Solid tumors associated with multiple endocrine neoplasias

We present an update on molecular and clinical genetics of solid tumors associated with the various multiple endocrine neoplasias (MEN) syndromes. MEN type 1 (MEN1) describes the association of pituitary, parathyroid, and pancreatic islet cell tumors with a variety of many other lesions. MEN type 2 (MEN2) conditions represent at least four different syndromes that associate pheochromocytoma with medullary thyroid carcinoma, hyperparathyroidism, and a number of other manifestations. Other pheochromocytoma-associated syndromes include von Hippel-Lindau disease; neurofibromatosis 1; the recently defined paraganglioma syndromes type 1, 3, and 4; Carney-Stratakis syndrome; and the Carney triad. Carney-Stratakis syndrome is characterized by the association of paragangliomas and familial gastrointestinal stromal tumors. In the Carney triad, patients can manifest gastrointestinal stromal tumors, lung chondroma, paraganglioma, adrenal adenoma and pheochromocytoma, esophageal leiomyoma, and other conditions. The Carney complex is yet another form of MEN that is characterized by skin tumors and pigmented lesions, myxomas, schwannomas, and various endocrine neoplasias.

[Multiple endocrine neoplasia type I]

Multiple endocrine neoplasia type I (MEN1) is a rare hereditary cancer syndrome, which is manifested as a variety of endocrine and non-endocrine tumours and lesions caused by specific germline mutations of the MEN1 gene, a tumour suppressor gene. The detection of these germline mutations allows the early identification of affected, possibly still asymptomatic patients. The combined use of genetic and clinical tools for the diagnosis of MEN1-associated tumours substantially improves both the course of the disease and the quality of life of affected patients. This review summarizes the relevant morphological and clinical features of MEN1-associated endocrine and non-endocrine neoplasms and lesions.

Genetic screening for multiple endocrine neoplasia syndrome type 1 (MEN-1): when and how

Multiple endocrine neoplasia syndrome type 1 (MEN1) syndrome has benefited from the identification of the gene whose mutations account for the genetic susceptibility to develop endocrine tumors. Asymptomatic MEN1 mutant carriers need to be clearly recognized because the gene-related mutations confer a high risk of multiple primary cancers, occur at younger ages, and affect multiple family members who inherit the cancer-predisposing genetic mutation.