What is the Difference Between MEN1 and MEN2?

Multiple Endocrine Neoplasia (MEN) is a group of autosomal dominant inherited syndromes characterized by the occurrence of tumors involving two or more endocrine glands. The two most common types are MEN1 and MEN2. The main differences between MEN1 and MEN2 are the specific gene mutations involved and the organs affected:

• MEN1: Caused by mutations in the MEN1 gene. MEN1 syndrome usually causes tumors in the pituitary gland, parathyroid gland, or pancreas. The most common condition associated with MEN1 is hyperparathyroidism, which can cause symptoms such as kidney stones, weakness, and bone pain. Other conditions associated with MEN1 include pituitary adenoma, characterized by headaches, absence of menses during or after puberty, and lactation for no known reason.
• MEN2: Caused by mutations in the RET proto-oncogene. MEN2 syndrome usually causes tumors in the thyroid gland, parathyroid gland, or adrenal gland. MEN2 has two subtypes: MEN2A and MEN2B. MEN2A is characterized by the presence of medullary thyroid cancer and adrenal gland tumors called pheochromocytomas. MEN2B is the same as MEN2A but also includes nerve tumors in the chest and eyelids.

Genetic testing is more complex for MEN1 due to a general lack of mutational hotspots, and the benefits of genetic testing are less straightforward because there are no preventative strategies that can be employed to prevent or cure MEN1-associated tumors. In contrast, genetic testing for MEN2 is clinically beneficial for at-risk patients, as prophylactic thyroidectomy can be performed to address the risk of developing medullary thyroid cancer.

Comparative Table: MEN1 vs MEN2

Multiple Endocrine Neoplasia 1 (MEN1) and Multiple Endocrine Neoplasia 2 (MEN2) are rare disorders of the endocrine system. Here is a table comparing the differences between MEN1 and MEN2:

MEN1 results from inactivating mutations in and around the menin protein's long open reading frame, while MEN2 results from activating mutations in the Ret proto-oncogene. MEN1 is characterized by the combined occurrence of tumors of the parathyroids, pancreatic islet cells, and anterior pituitary, while MEN2 involves medullary thyroid cancer, adrenal paragangliomas, and phaeochromocytomas.