MEN1 is an inherited genetic syndrome generally caused by a mutation in the menin gene. All patients develop primary hyperparathyroidism with 4-gland hyperplasia (Some can also have a CDKN1b mutation instead of a menin mutation) , and many patients develop pituitary tumors and/or pancreatic neuroendocrine tumors, all of which secrete hormones and therefore cause a variety of other symptoms. Other tumors that can be associated with the syndrome include adrenal or small bowel tumors. Diagnosis is made through germline genetic testing as well as a detailed family history. Affected patients require lifelong screening and surveillance for associated neuroendocrine tumors as well as surgical intervention when tumors are diagnosed.
Testing for MEN1 should be done in young (less than 30-40 years old) patients with primary hyperparathyroidism, 4-gland hyperplasia, and patients with 2 or more associated tumors.