Causes

Neurofibromatosis is caused by genetic defects (mutations) that either are passed on by a parent or occur spontaneously at conception. The specific genes involved depend on the type of neurofibromatosis:

• NF1. The NF1 gene is located on chromosome 17. This gene produces a protein called neurofibromin that helps regulate cell growth. The mutated gene causes a loss of neurofibromin, which allows cells to grow uncontrolled.
• NF2. The NF2 gene is located on chromosome 22, and produces a protein called merlin (also called schwannomin), which suppresses tumors. The mutated gene causes a loss of merlin, leading to uncontrolled cell growth.
• Schwannomatosis. So far, two genes are known to cause schwannomatosis. Mutations of the genes SMARCB1 and LZTR1, which suppress tumors, are associated with this type of neurofibromatosis.