Multiple Endocrine Neoplasia Type 1 (MEN1)
Multiple Endocrine Neoplasia Type 1 (MEN1) is a rare inherited condition that causes tumours to develop in hormone-producing (endocrine) glands.
Overview
Multiple Endocrine Neoplasia Type 1 (MEN1) is a rare inherited condition that causes tumours to develop in hormone-producing (endocrine) glands. The glands most commonly affected are the parathyroid glands, the pancreas (neuroendocrine cells), and the pituitary gland. Because hormones regulate many body functions, MEN1 can affect several systems in the body.
Causes and Genetics
MEN1 is caused by changes (mutations) in the MEN1 gene. This gene provides instructions for making a protein called menin, which helps control cell growth. When menin does not function properly, cells may grow in an uncontrolled way, leading to tumour formation. MEN1 is inherited in an autosomal dominant pattern, meaning a person only needs one altered copy of the gene to have the condition. An affected individual has a 50% chance of passing the condition on to each child. In some cases, MEN1 occurs for the first time in a family due to a new (de novo) genetic change.
Symptoms and Features
Symptoms depend on the site of tumours and the hormones produced. The most commonly affected glands are the parathyroid glands, pituitary gland and pancreas.
Parathyroid Tumours
- Parathyroid tumours cause raised calcium levels (primary hyperparathyroidism). High calcium may be associated with kidney stones, abdominal pain, constipation, nausea, excessive thirst, frequent urination, fatigue, low mood, bone pain, reduced bone density and increased risk of fractures
Pituitary and Pancreatic Tumours
- Pituitary tumours may cause headaches and visual disturbance. Prolactin-secreting tumours: irregular or absent periods, reduced fertility, breast milk production. Growth hormone-secreting tumours: enlargement of hands and feet, changes in facial features. ACTH-secreting tumours: features of Cushing's syndrome
- Pancreatic neuroendocrine tumours may produce insulin (causing low blood sugar episodes), gastrin (causing severe reflux and stomach ulcers), glucagon (causing high blood sugar and skin rash), or may be non-functioning
Treatment
Patients are usually managed through specialist endocrine and oncology centres. Family members may require genetic counselling and screening.
Research and Future Directions
Ongoing research is focused on improving early tumour detection, understanding how MEN1 gene changes lead to tumour formation, and developing more targeted treatments. Studies are assessing improved imaging techniques, personalised treatment approaches and long-term outcomes for people living with MEN1. Advances in genetic testing and surveillance strategies continue to improve earlier diagnosis and proactive management.