There are two types of multiple endocrine neoplasia. They are MEN1 and MEN2. Although their names are similar, they are separate conditions. This information is about MEN2.
Your body is made up of tiny building blocks called cells. Inside every cell is a set of genes. These genes are the instructions the cell needs to work normally. Sometimes, the structure inside a gene is permanently changed, so the gene no longer gives the correct instructions. This change is called a gene mutation.
People with multiple endocrine neoplasia type 2 (MEN2) are born with a mutation in the RET gene. If you have a mutation in this gene, you are more likely to develop certain types of tumour.