Germline mutation profile of MEN1 in multiple endocrine neoplasia type 1: search for correlation between phenotype and the functional domains of the MEN1 protein.

Multiple Endocrine Neoplasia type 1 (MEN1) is an autosomal dominant disease characterized by endocrine tumors of the parathyroids, the pancreatic islets, and the anterior pituitary. The MEN1 gene encodes menin, a nuclear protein interacting with JunD/AP1, Smad3, NFkappaB, and other proteins involved in transcription and cell growth regulation. Here, by exhaustive sequence analysis of 170 probands/families collected through a French clinical network, we identified 165 mutations located in coding parts of the MEN1 gene, which represent 114 distinct MEN1 germline alterations. These mutations have been included in a MEN1-locus specific database available on the world wide web together with approximately 240 germline and somatic MEN1 mutations listed from international published data. Our mutation series included 56 frameshifts, 23 nonsense, 27 missense, and eight deletion or insertion in-frame mutations. Mutations were spread over the entire coding sequence. Taken together, most missense and in-frame MEN1 genomic alterations affect one or all domains of menin interacting with JunD [codons 1-40; 139-242; 323-428], Smad3 [distal to codon 478], and NFkappaB [codons 276-479], three major effectors in transcription and cell growth regulation. No correlation has been observed between genotype and MEN1 phenotype. We suggest that the knowledge of structure and location of a specific mutation has not been useful in clinical practice for the follow-up of affected patients and asymptomatic gene carriers. Our results provide the largest series of MEN1 mutations published to date. They will be a useful tool for further studies focusing on the functional effects of missense mutations and understanding which mechanisms or pathways related to multiple menin interactions might be involved in tumorigenesis of endocrine cells.

Pituitary disease in MEN type 1 (MEN1): data from the France-Belgium MEN1 multicenter study.

To date, data on pituitary adenomas in MEN type 1 (MEN1) still have to be evaluated. We analyzed the data of a large series of 324 MEN1 patients from a French and Belgian multicenter study. Data on pituitary disease were compared with those from 110 non-MEN1 patients with pituitary adenomas, matched for age, year of diagnosis, and follow-up period. Genetic analysis of the MEN1 gene was performed in 197 of the MEN1 patients. In our MEN1 series, pituitary disease occurred in 136 of 324 (42%), less frequently than hyperparathyroidism (95%, P < 0.001) and endocrine enteropancreatic tumors (54%, P < 0.01). Mean age of onset of pituitary tumors was 38.0+/-15.3 yr (range, 12-83 yr). Pituitary disease was associated with hyperparathyroidism in 90% of cases, with enteropancreatic tumors in 47%, with adrenal tumors in 16%, and with thoracic neuroendocrine tumors in 4%. Pituitary disease was the initial lesion of MEN1 in 17% of all MEN1 patients. MEN1 pituitary adenomas were significantly more frequent in women than in men (50% vs. 31%, P < 0.001). Among the 136 pituitary adenomas, there were 85 prolactinomas and 12 GH-secreting, 6 ACTH-secreting, 13 cosecreting, and 20 nonsecreting tumors. Eighty-five percent of MEN1-related pituitary lesions were macroadenomas (vs. 42% in non-MEN1 patients, P < 0.001), including 32% of invasive cases. Among secreting adenomas, hormonal hypersecretion was normalized, after treatment, in only 42% (vs. 90% in non-MEN1 patients, P < 0.001), with a median follow-up of 11.4 yr. No correlation was found between the type of MEN1 germ-line mutation and the presence or absence of pituitary adenoma. Our study, based on a large group of MEN1 patients, shows that pituitary adenomas occur in 42% of the cases and are characterized by a larger size and a more aggressive presentation than without MEN1.