Neurofibromatosis (NF) is a set of genetic disorders that can cause tumors to develop and grow along various types of nerves. The tumors may also affect the development of non-nervous system tissues such as skin and bone.
There are three types of NF tumors that result from mutation or loss of different tumor suppressor genes:
- Neurofibromatosis type 1 (NF1) is the most frequent inherited cause of brain and nerve tumors. One in every 3,000 children is born with NF1, making it also one of the most common inherited human diseases worldwide. Enlargement and deformation of bones may also occur. Approximately 50% of people with NF1 also have learning disabilities. NF1 is caused by a mutation or loss of the tumor suppressor gene NF1.
- Neurofibromatosis type 2 (NF2) is much rarer, occurring in one in 25,000 births. NF2 is characterized by the development of multiple tumors on the cranial and spinal nerves. The hallmark of NF2 is the formation of tumors that affect auditory nerves. Hearing loss beginning in the teens or early twenties is typically the first symptom of NF2. NF2 is caused by a mutation or loss of the tumor suppressor gene NF2.
- Schwannomatosis is even rarer than NF2, affecting one in 40,000 individuals. SImilar to NF1 and NF2, Schwannomatosis tumors can develop on cranial, spinal and/or peripheral nerves. Although patients with Schwannomatosis do not have learning disabilities, they experience chronic pain and occasionally numbness, tingling and weakness. The candidate Schwannomatosis tumor suppressor gene is named INI1.