Neurofibromatosis: Neurofibromatosis is a genetic disorder of the nervous system. It mainly affects how nerve cells form and grow. It causes tumors to grow on nerves. You can get neurofibromatosis from your parents, or it can happen because of a mutation (change) in your genes. Once you have it, you can pass it along to your children. Usually the tumors are benign, but sometimes they can become cancerous. There are three types of neurofibromatosis: Type 1 (NF1) causes skin changes and deformed bones. It usually starts in childhood. Sometimes the symptoms are present at birth. Type 2 (NF2) causes hearing loss, ringing in the ears, and poor balance. Symptoms often start in the teen years. Schwannomatosis causes intense pain. It is the rarest type. Doctors diagnose the different types based on the symptoms. Genetic testing is also used to diagnose NF1 and NF2. There is no cure. Treatment can help control symptoms. Depending on the type of disease and how serious it is, treatment may include surgery to remove tumors, radiation therapy, and medicines.