Approximately half (50%) of all people with neurofibromatosis type 1 inherit the disorder. It is inherited in an autosomal dominant pattern, which means that only one copy of the defective gene has to be inherited for a baby to be born with NF1. Therefore, each child of a parent with NF1 runs a 50 percent risk of getting the disorder.

In the other half of NF1 cases, a person will have no family history of the disease. The mutation is new and has likely occurred early in life (during the development of the embryo). New mutations are frequently the cause of NF1 because the NF1 gene is very large, making it more likely to have a mutation.