Rare hereditary endocrine cancer syndrome characterised primarily by tumours of the parathyroid glands, endocrine gastroenteropancreatic tract, and anterior pituitary

Aetiology

• Autosomal dominant inheritance
• 'Classic' tumour suppressor in endocrine tissues
• Mutations occur throughout MEN1 gene located on chromosome 11q13
• Mutations typically result in loss/reduced protein function

Pathophysiology

• Exact pathogenesis unclear
• MEN1 genes are involved in how a cell responds to DNA damage, chromatin remodelling and cell signalling pathway regulation e.g. PI3K/mTOR
• Will typically present with a pituitary adenoma; it is also possible for the patient to develop hyperparathyroidism and pancreatic tumours, such as insulinoma
• Can develop many other tumours - thymic/bronchial carcinoids, gastric carcinoid, functioning/non-functioning adrenal, soft tissue tumours e.g. lipomas, angiofibromas

Prognosis

• 50% of affected individuals will die as a direct result of the disease
• Premature mortality observed in high proportion of affected individuals
• Leaading causes of excess deaths are malignant pancreatic neuroendocrine tumour and thymic carcinoids

Investigations

Indications for germline MEN1 testing

• Meeting clinical criteria for MEN1 (i.e. 2+ MEN1-associated tumours or diagnosis of familial MEN1)
• Features suspicious of MEN1
• First degree relative of family member with a known MEN1 tumour