Genetics of Endocrine and Neuroendocrine Neoplasias (PDQ®)–Health Professional Version

Multiple Endocrine Neoplasia Type 4

Introduction

Multiple endocrine neoplasia type 4 (MEN4) is a novel, rare syndrome with clinical features that overlap with the other MEN syndromes. The most common phenotype of the 19 established cases of MEN4 that have been described to date is primary hyperparathyroidism (PHPT), followed by pituitary adenomas. MEN4 is caused by germline pathogenic variants in the tumor suppressor gene CDKN1B (12p13.1).[1] This syndrome was discovered initially in rats (MENX) [2] and later in humans (MEN4). The syndrome has the phenotype of being multiple endocrine neoplasia type 1 (MEN1)-like. The incidence of CDKN1B variants in patients with an MEN1-related phenotype is difficult to estimate, but it is likely to be in the range of 1.5% to 3.7%.[3-5] Pathogenic variants leading to the MEN4 phenotype are transmitted in an autosomal dominant fashion.

Clinical Diagnosis

PHPT due to parathyroid neoplasia affects approximately 80% of the reported cases of MEN4. PHPT occurs at a later age in MEN4 than in MEN1 (mean age ~56 y vs. ~25 y, respectively), with a female predominance.[6] There have been no reports of PHPT recurrence after surgical resection, which might indicate that PHPT in MEN4 represents an overall milder disease spectrum than in MEN1. Pituitary involvement in MEN4 is the second most common manifestation of the disease, affecting approximately 37% of the reported cases. Pituitary adenomas in MEN4 vary and include nonfunctional, somatotropinoma, prolactinoma, or corticotropinoma types. The age at diagnosis for these lesions also varies widely, from 30 years to 79 years. The youngest patient reported to have MEN4 presented at age 30 years with acromegaly.[2] Pancreatic neuroendocrine tumors (NETs) have been rare, with only a few cases reported. These include duodenopancreatic or gastrointestinal NETs that could be nonfunctioning or hormonally active and may secrete several substances, including gastrin, insulin, adrenocorticotropic hormone, or vasoactive intestinal polypeptide. Although adrenal neoplasia is a frequent finding in MEN1, only one case of nonfunctional bilateral adrenal nodules has been reported in MEN4.[5] Skin manifestations that are commonly reported in MEN1, such as lipomas, angiofibromas, and collagenomas, have not been reported in MEN4. There is no known genotype-phenotype correlation.

Genetics, Inheritance, and Genetic Testing

The CDKN1B variant codes for p27Kip1 (commonly referred to as p27 or KIP1), a putative tumor suppressor gene that regulates cell cycle progression. Alterations in this gene lead to a greater decrease in expression of p27 protein, triggering uncontrolled cell cycle progression. Although the loss of one allele of p27 is a frequent event in many human cancers, the remaining allele is rarely mutated or lost by loss of heterozygosity in human cancers.[7] Somatic mutations or germline pathogenic variants in CDKN1B have also been identified in patients with sporadic PHPT, small intestinal NETs, lymphoma, and breast cancer. These findings demonstrate a novel role for CDKN1B as a tumor susceptibility gene for other neoplasms.[8-10]

To date, only 19 cases having CDKN1B germline variants have been reported in the medical literature.[8] Thirteen pathogenic germline variants that have been frameshift, nonsense, or missense variants have been described.[11,12]

Index cases or individuals with MEN1-like features and negative results of MEN1 genetic testing are offered genetic counseling and testing for MEN4. Confirmation of an MEN4 diagnosis is only made with genetic testing for CDKN1B variants. In clinical practice, patients with asymptomatic or symptomatic PHPT who are also young (typically <30 y) and have multigland disease, parathyroid carcinoma, or atypical adenoma, or those with a family history or evidence of syndromic disease and negative for MEN1 or RET, are candidates for genetic testing for CDKN1B using accredited laboratories.[8] For those with proven disease, screening is also offered to a first-degree relative with or without MEN1 features. The identification of a germline CDKN1B variant should prompt periodic clinical biochemical screening for MEN4.

Surveillance

Surveillance of CDKN1B pathogenic variant carriers should be performed, though guidelines have yet to be established.[8,13] Currently, surveillance is primarily clinical and concentrates on evidence of growth hormone excess, with annual biochemical evaluation for insulin-like growth factor-1 and annual blood work for PHPT.[13] For known carriers, surveillance begins at adolescence. The role of imaging has not been established.

Interventions

For parathyroid and pituitary disease, the treatment is surgical, in accordance with treatment for other familial syndromes. (Refer to the MEN1 section of this summary for more information.)

Outcomes

A study of 293 MEN1 pathogenic variant–positive cases and 30 MEN1 pathogenic variant–negative cases, all with the MEN1 phenotype, showed that the pathogenic variant–negative cohort developed disease manifestations later in life, with improved life expectancy.[14] One of the limitations in applying this finding to MEN4 is that only 1 of these 30 MEN1-negative patients was CDKN1B positive.

References

Marinoni I, Pellegata NS: p27kip1: a new multiple endocrine neoplasia gene? Neuroendocrinology 93 (1): 19-28, 2011. [PUBMED Abstract]
Pellegata NS, Quintanilla-Martinez L, Siggelkow H, et al.: Germ-line mutations in p27Kip1 cause a multiple endocrine neoplasia syndrome in rats and humans. Proc Natl Acad Sci U S A 103 (42): 15558-63, 2006. [PUBMED Abstract]
Georgitsi M, Raitila A, Karhu A, et al.: Germline CDKN1B/p27Kip1 mutation in multiple endocrine neoplasia. J Clin Endocrinol Metab 92 (8): 3321-5, 2007. [PUBMED Abstract]
Agarwal SK, Mateo CM, Marx SJ: Rare germline mutations in cyclin-dependent kinase inhibitor genes in multiple endocrine neoplasia type 1 and related states. J Clin Endocrinol Metab 94 (5): 1826-34, 2009. [PUBMED Abstract]
Molatore S, Marinoni I, Lee M, et al.: A novel germline CDKN1B mutation causing multiple endocrine tumors: clinical, genetic and functional characterization. Hum Mutat 31 (11): E1825-35, 2010. [PUBMED Abstract]
Lee M, Pellegata NS: Multiple endocrine neoplasia type 4. Front Horm Res 41: 63-78, 2013. [PUBMED Abstract]
Philipp-Staheli J, Payne SR, Kemp CJ: p27(Kip1): regulation and function of a haploinsufficient tumor suppressor and its misregulation in cancer. Exp Cell Res 264 (1): 148-68, 2001. [PUBMED Abstract]
Alrezk R, Hannah-Shmouni F, Stratakis CA: MEN4 and CDKN1B mutations: the latest of the MEN syndromes. Endocr Relat Cancer 24 (10): T195-T208, 2017. [PUBMED Abstract]
Malanga D, De Gisi S, Riccardi M, et al.: Functional characterization of a rare germline mutation in the gene encoding the cyclin-dependent kinase inhibitor p27Kip1 (CDKN1B) in a Spanish patient with multiple endocrine neoplasia-like phenotype. Eur J Endocrinol 166 (3): 551-60, 2012. [PUBMED Abstract]
Occhi G, Regazzo D, Trivellin G, et al.: A novel mutation in the upstream open reading frame of the CDKN1B gene causes a MEN4 phenotype. PLoS Genet 9 (3): e1003350, 2013. [PUBMED Abstract]
Georgitsi M: MEN-4 and other multiple endocrine neoplasias due to cyclin-dependent kinase inhibitors (p27(Kip1) and p18(INK4C)) mutations. Best Pract Res Clin Endocrinol Metab 24 (3): 425-37, 2010. [PUBMED Abstract]
Lee M, Pellegata NS: Multiple endocrine neoplasia syndromes associated with mutation of p27. J Endocrinol Invest 36 (9): 781-7, 2013. [PUBMED Abstract]
Wasserman JD, Tomlinson GE, Druker H, et al.: Multiple Endocrine Neoplasia and Hyperparathyroid-Jaw Tumor Syndromes: Clinical Features, Genetics, and Surveillance Recommendations in Childhood. Clin Cancer Res 23 (13): e123-e132, 2017. [PUBMED Abstract]
de Laat JM, van der Luijt RB, Pieterman CR, et al.: MEN1 redefined, a clinical comparison of mutation-positive and mutation-negative patients. BMC Med 14 (1): 182, 2016. [PUBMED Abstract]