Molecular analysis of MEN 1 gene in sixty three suspected carriers of Multiple Endocrine Neoplasia type 1 (MEN 1): First series in Argentina

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 292-305-MEN1, MEN2 & Pheochromocytomas
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-300
María Lorena Viale1, Mara Pa Serra1, Tomas Fernandez Gianotti1, Oscar Domingo Bruno2, Marta Beatriz Barontini3, Debora Katz4, Adriana Graciela Diaz2, Andrea Elina Kozak1, Marta Iris Balzaretti1, Maria Eugenia Escobar5, Angela R Solano6, Susana Belli7, Maria Fabiana Russo Picasso1 and Patricia Fainstein Day*1
1Italian Hospital, Buenos Aires, Argentina, 2Hospital de Clinicas, Buenos Aires, Argentina, 3Centro de Invest Endo (CEDIE), Capital Federal, Argentina, 4FLENI, Argentina, 5Hospital de Nios Ricardo Gutierrez, Buenos Aires, Argentina, 6Univ of Buenos Aires, Buenos Aires, Argentina, 7Durand Hospital, Buenos Aires, Argentina
Background: MEN 1 is an autosomal dominantly inherited syndrome characterized by parathyroid, gastroenteropancreatic and anterior pituitary tumors. The most prevalent clinical presentation is primary hyperparathyroidism (95%), followed by gastroenteropancreatic neuroendocrine tumors (70%) and pituitary tumors (40%). The MEN1 gene is a tumor suppressor gene located in chromosome 11q13 and codes for menin, a nuclear protein of 610 aminoacids. Genetic diagnosis requires the sequencing of the whole DNA coding sequence and is warranted in patients with two or more of the characteristic tumors (MEN1 classic patient, MC), their first-degree relatives, or patients with special characteristics, like very young carriers of one of the tumors (MEN1 non classic patient, MNC).

AIM: The purpose of this study was to evaluate the MEN1 gen mutations in patients with clinical features of MEN 1 in Argentina.

Subjects: We studied 63 potential carriers: 30 index-cases of wich 25 were MC, (mean age 39,8 +/- 10,8 years;17 women) and 5 patients MNC(mean age 18,4 +/- 2,1 years; 1 women).In the group of MEN1 classic patient; 19 were sporadic (FCE) and 6 were familiar (FCM). We also studied 33 first-degree relatives. The DNA of 66 healthy subjects (mean age 34,3 +/- 0,7 years, 50 women) was analysed as control group.

Methods: Genomic DNA was obtained from peripheral blood leukocytes. Exons 2-10 and intronic flanking regions of the MEN 1 gene were amplified by PCR using specific primers. The amplification products were separated by electrophoresis in agarose gel, stained with ethidium bromide and examined under UV light. The DNA fragments were sequenced after being manually labeled with ddNTP33 and in latter dates, by automatic sequencing. Novel mutations were either verified in both sense and antisense directions and eventually confirmed by RFLP-PCR. Polymorphisms and missense novel mutations were verified by sequencing 104 alelles of a normal control population.

Results: We found germline mutations in 64% of MC and in 40% of MNC. Within the group of the classic patient we found germline mutations in 83% of MCF and 58% of MCE. We also found that polymorphisms c.1621G>A (A541T), c.512G>A (R171Q) and c.1254C>T(D418D) had an allelic prevalence of 7,6%, 1,5% and 31,8% respectively in the control group.

Conclusions: We found germline mutations in 64 % of MEN1 classic patients and 30% of first-degree relatives. MEN1 mutations were distributed throughout the entire gene and included nonsense, frameshift and missense mutations like other series that has been published. We did not find a correlation between genotype and phenotype.

(1) Agarwal SK, Guru SC, Heppner C, Erdos MR, Collins RM, Park SY, Saggar S, Chandrasekharappa SC, Collins FS, Spiegel AM, Marx SJ, Burns AL. Menin interacts with the AP1 transcription factor JunD and represses JunD-activated transcription. Cell. 1999;96:143-52. (2) Brandi ML, Gagel RF, Angeli A et al. Guidelines for diagnosis an therapy fo MEN type 1 and type 2. J Clin Endocrinol Metab 2001;86:5658-5671. (3) Lemos MC, Harding B, Reed AA, Jeyabalan J, Walls GV, Bowl MR, Sharpe J, Wedden S, Moss JE, Ross A, Davidson D, Thakker RV. Genetic background influences embryonic lethality and the occurrence of neural tube defects in Men1 null mice: relevance to genetic modifiers. J Endocrinol. 2009; 1:133-42.

Nothing to Disclose: MLV, MPS, TF, ODB, MBB, DK, AGD, AEK, MIB, MEE, ARS, SB, MFR, PF

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