Neurofibromatosis type 1 (NF1) is a multi-symptom neurogenetic disorder caused by heterozygous loss-of-function mutations in the neurofibromin 1 (NF1) gene, which encodes neurofibromin, a tumor suppressor that inhibits signaling via the small GTPase rat sarcoma virus (RAS) subfamily of proteins. Here, NF1 is linked to neurofibromatosis type 1.