Clinical and genetic features of patients with multiple endocrine tumors who have neither family history nor MEN1 germline mutations

A Japanese Family Meeting the Clinical Diagnostic Criteria for MEN1 with a MEN1 Variant of Uncertain Significance

Multiple gastroenteric, pancreatic, and pituitary neuroendocrine neoplasms (NENs) were diagnosed in a 74-year-old man with a history of primary hyperparathyroidism (PHPT). Germline testing demonstrated a variant of MEN1 (c.1694T>A, p.L565Q), whose pathogenicity was classified as a variant of uncertain significance (VUS) according to the ACMG/AMP guidelines. The same germline variant was detected in the patient's son and daughter, who also showed PHPT or hypercalcemia and met the clinical diagnostic criteria for multiple endocrine neoplasia type 1 (MEN1). During surveillance of the son, multiple pancreatic tumors suggestive of NENs were detected. The pathogenicity of the current MEN1 variant was re-evaluated as likely pathogenic, based on additional family data.

MEN1 gene analysis in patients with primary hyperparathyroidism: 10-year experience of a single institution for thyroid and parathyroid care in Japan

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disease. Primary hyperparathyroidism is known to occur at an early age in MEN1 patients. In MEN1 patients, special care regarding not only surgery for hyperparathyroidism but also other MEN1-related tumors is required. Between 1998 and 2007, 482 patients, including 16 whose hyperparathyroidism was discovered by family screening for MEN1, underwent surgical therapy for primary hyperparathyroidism at our institution. We recommended MEN1 gene analysis for patients having one of the following clinicopathological features: 1) age younger than 30 years old; 2) enlargement of multiple glands; 3) coexistence or presence of past history of MEN1-related tumors; or 4) family history of hyperparathyroidism or MEN1-related tumors. Sixty patients had at least one of the above features and were recommended for genetic analysis. Thirty-nine of these patients consented to undergo MEN1 genetic analysis and 16 (41%) showed MEN1 mutation. Pathological examination confirmed multiglandular parathyroid hyperplasia in 15 cases. Subject to this strategy, MEN1 index patients in Japan could be detected efficiently and selected for appropriate therapies for hyperparathyroidism and MEN1-related tumors.

Germ-line mutations in p27Kip1 cause a multiple endocrine neoplasia syndrome in rats and humans

MENX is a recessive multiple endocrine neoplasia-like syndrome in the rat. The tumor spectrum in MENX overlaps those of human multiple endocrine neoplasia (MEN) types 1 and 2. We mapped the MenX locus to the distal part of rat chromosome 4, excluding the homologs of the genes responsible for the MEN syndromes (RET and MEN1) and syndromes with an endocrine tumor component (VHL and NF1). We report the fine mapping of the disease locus and the identification of a homozygous frameshift mutation in Cdkn1b, encoding the cyclin-dependent kinase inhibitor p27(Kip1). As a consequence of the mutation, MENX-affected rats show dramatic reduction in p27(Kip1) protein. We have identified a germ-line nonsense mutation in the human CDKN1B gene in a MEN1 mutation-negative patient presenting with pituitary and parathyroid tumors. Expanded pedigree analysis shows that the mutation is associated with the development of an MEN1-like phenotype in multiple generations. Our findings demonstrate that germ-line mutations in p27(Kip1) can predispose to the development of multiple endocrine tumors in both rats and humans.