MEN4 and CDKN1B mutations: the latest of the MEN syndromes

Abstract

Multiple endocrine neoplasia (MEN) refers to a group of autosomal dominant disorders with generally high penetrance that lead to the development of a wide spectrum of endocrine and non-endocrine manifestations. The most frequent among these conditions is MEN type 1 (MEN1), which is caused by germline heterozygous loss-of-function mutations in the tumor suppressor geneMEN1. MEN1 is characterized by primary hyperparathyroidism (PHPT) and functional or nonfunctional pancreatic neuroendocrine tumors and pituitary adenomas. Approximately 10% of patients with familial or sporadic MEN1-like phenotype do not haveMEN1mutations or deletions. A novel MEN syndrome was discovered, initially in rats (MENX), and later in humans (MEN4), which is caused by germline mutations in the putative tumor suppressorCDKN1B. The most common phenotype of the 19 established cases of MEN4 that have been described to date is PHPT followed by pituitary adenomas. Recently, somatic or germline mutations inCDKN1Bwere also identified in patients with sporadic PHPT, small intestinal neuroendocrine tumors, lymphoma and breast cancer, demonstrating a novel role forCDKN1Bas a tumor susceptibility gene for other neoplasms. In this review, we report on the genetic characterization and clinical features of MEN4.