Neurofibromatosis is a genetic disorder that causes tumors in the nervous system. Tumors develop in the nerves or the tissue that surrounds the nerves, called myelin sheath. Neurofibromatosis is divided into three types, neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis. The type is determined by the specific genes that are affected.

This articles discusses NF1, the most common neurofibromatosis. It affects the nerves outside the brain and spinal cord, called peripheral nerves.

The Nervous System
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NF is caused by a change in a specific gene. The gene normally makes proteins that help control growth in the nerves. Since the gene is defective, these proteins are not able to control growth, and tumors develop.

In many cases, the abnormal gene is inherited from a parent. A person with the inherited form of NF has a 50% chance of passing the abnormal gene to each child. Any parents, children, and siblings of an affected individual should be considered at risk for NF. However, the gene change can occur in a person with no family history of NF.

Schwannomatosis—mutation of the SMARCB1/INI1 gene