What causes nf?

Neurofibromatosis? If by nf you mean neurofibromatosis, it is either of two diseases that are inherited dominantly (parent to child, 50% odds). You can help yourself by learning more about them and being a good partner with your physician.
Change in a gene. Nf is usually caused by a random change in genes on a chromosome. This mutation is present when the egg is fertilized, so it affects every cell in the body.
Mostly genetic. Neurofibromatosis,mostly inherited problem, or mutation with degrees involvement from mild to severe. Neurofibroma benign tumor that originates from the nerve cell in skin or jut under the skin.Type1 usually appears in children with brown flat skin spots, freckling in armpits, and soft tumors under the skin and sometimes bone deformity.Type2 usually benign brain tumors vestibular/acoutic neuromas.