 NF1 is an autosomal dominant disorder, but approximately half of NF1 cases arise from "de novo" mutations.NF1 has high phenotypic variability, with members of the same family with the same mutation displaying different symptoms and symptom intensities.Café-au-lait spots are the most common sign of NF1, but other symptoms include lisch nodules of iris, cutaneous neurofibromas (CNF), plexiform neurofibromas (PN), skeletal defects, optic nerve gliomas, life-threatening malignant peripheral nerve sheath tumors (MPNST), attention deficits, learning deficits and other cognitive disabilities.