Neurofibromatosis (NF) occurs in one in 4,000 persons. Neurofibromatosis is an autosomal dominant condition caused by a gene on chromosome 17, which is inherited from a parent with the disease (in half of the cases). A parent with neurofibromatosis has a 50/50 chance of having a child with the disease. Neurofibromatosis may also be the result of a new gene change (mutation). Half of neurofibromatosis cases are caused by a new mutation and are not inherited.