This document is a quick and concise evidence-based summary to provide additional information, instruction, or guidance to complement a treatment protocol or clinical resource document.
The key endocrine tumours associated with MEN type 1 and MEN type 4 are:
- Parathyroid tumours or hyperplasia (which manifests as primary hyperparathyroidism)
- Anterior pituitary adenomas
- Gastroduodenopancreatic neuroendocrine tumours (GDP-NET).
The diagnosis of MEN type 1 can be made on clinical, familial or genetic criteria.
A clinical diagnosis of MEN type 1 is established in an individual with two or more key MEN1-associated tumours.
A familial diagnosis of MEN type 1 is established in an individual with one key MEN1-associated tumour and a first degree relative with a clinical diagnosis of MEN1 (and not known to have a pathogenic variant in another endocrine tumour predisposition gene, e.g. CDKN1B, PRKAR1A, AIP, CDC73).
A genetic diagnosis of MEN1 is established in an individual (who may be unaffected, and has not yet developed serum biochemical or radiological abnormalities due to tumour development) in whom identification of a germline MEN1 pathogenic variant has been identified.
A diagnosis of familial isolated primary hyperparathyroidism (FIHP) may arise due to MEN1 pathogenic variants and is characterised by the occurrence of hereditary PHPT without the occurrence of other MEN1-associated tumours.
The diagnosis of MEN type 4 is made on genetic criteria only.
The MEN type 1 phenotype can occur in both a sporadic (no family history of MEN1 tumours) or familial setting, including:
- an individual with a personal and family history of MEN1-associated tumours, and WITH/WITHOUT an identified MEN1 pathogenic variant (or another endocrine predisposition gene*)
- an individual without a personal history of MEN1-associated tumours in a family who has MEN1-associated tumours WITH/WITHOUT an identified MEN1 pathogenic variant.
* In up to 30% of MEN1 patients who are diagnosed based on clinical criteria, MEN1 pathogenic variants are not identified.r