The Role of Molecular Genetics in Screening for Multiple Endocrine Neoplasia Type 1

Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited tumor syndrome, characterized by the development of multiple neuroendocrine tumors (NETs) in a single patient. Major manifestations include primary hyperparathyroidism, gastro-entero-pancreatic neuroendocrine tumors, and pituitary adenomas. In addition to these main NETs, various combinations of more than 20 endocrine and non-endocrine tumors have been described in MEN1 patients. Despite advances in diagnostic techniques and treatment options, which are generally similar to those of sporadic tumors, patients with MEN1 have a poor life expectancy, and the need for targeted therapies is strongly felt. MEN1 is caused by germline heterozygous inactivating mutations of the MEN1 gene, which encodes menin, a tumor suppressor protein. The lack of a direct genotype–phenotype correlation does not permit the determination of the exact clinical course of the syndrome. One of the possible causes of this lack of association could be ascribed to epigenetic factors, including microRNAs (miRNAs), single-stranded non-coding small RNAs that negatively regulate post-transcriptional gene expression. Some miRNAs, and their deregulation, have been associated with MEN1 tumorigenesis. Recently, an extracellular class of miRNAs has also been identified (c-miRNAs); variations in their levels showed association with various human diseases, including tumors. The aim of this review is to provide a general overview on the involvement of miRNAs in MEN1 tumor development, to be used as possible targets for novel molecular therapies. The potential role of c-miRNAs as future non-invasive diagnostic and prognostic biomarkers of MEN1 will be discussed as well.

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Phenocopies of multiple endocrine neoplasia type 1: role of the genes, associated with the development of pituitary adenomas

Problems of Endocrinology ◽

10.14341/probl20166244-10 ◽

2016 ◽

Vol 62 (4) ◽

pp. 4-10

Author(s):

Elizaveta O. Mamedova ◽

Natalya G. Mokrysheva ◽

Ekaterina A. Pigarova ◽

Elena G. Przhiyalkovskaya ◽

Evgeny V. Vasilyev ◽

...

Keyword(s):

Pituitary Adenomas ◽

Multiple Endocrine Neoplasia ◽

Multiple Endocrine Neoplasia Type ◽

New Genes ◽

Endocrine Neoplasia ◽

Endocrine Neoplasia Type ◽

Exon 1 ◽

Aip Gene

Background. Absence of detectable MEN1 mutations in a patient with multiple endocrine neoplasia type 1 (MEN1) phenotype may disprove the hereditary predisposition and the necessity of a lifelong regular screening for detecting the remaining components of the syndrome, and the examination of the first-degree relatives. Nevertheless, there may be other genes involved in the co-occurrence of several MEN1-associated tumors. Aim — to determine the role of genes, associated with the development of familial pituitary adenomas (PA), and genes, presumably involved in pathogenesis of sporadic PA, in the development of MEN1 phenocopies with PA as one of components.Material and methods. 23 patients with MEN1 phenocopy were included in the study. The patients underwent next-generation sequencing (NGS) (Ion TorrentTM PGMTM, Thermo Fisher Scientific — Life Technologies, USA) using a panel of candidate genes (MEN1, CDKN1B, PRKAR1A, AIP, SDHA, SDHB, SDHC, SDHD, GNAS, PRKCA, CDKN2A, CDKN2C, POU1F1, PTTG2).Results. In 1 (4%) female patient with acromegaly and primary hyperparathyroidism (PHPT) a germline heterozygous change in exon 6 of AIP gene c.911G>A (p.R304Q) was revealed. In four female patients with acromegaly and PHPT we revealed polymorphisms whose pathological significance is not defined: heterozygous change in exon 1 of PTTG2 gene c.134G>A (p.R45H), heterozygous change in intron 1 of PRKAR1A gene (c.–10G>C), heterozygous change in exon 5 of SDHB gene c.487T>C (p.S163P), heterozygous change in 3’-UTR of CDKN1B gene g.3897G>T (c*8G>T).Conclusions. The results of our study show that mutations in the majority of the examined genes associated with the development of hereditary and sporadic PA, do not cause the development of MEN1 phenocopies. The necessity to study AIP gene in all patients with MEN1 phenocopies needs further research. It is recommended to search for new genes, mutations in which could be the cause of the development of MEN1 phenocopies.

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