For instance, a specific in-frame deletion of codon 992 of NF1 (MIM: 613113) is associated with a milder phenotype characterized by café-au-lait spots and skinfold freckling and with the absence of cutaneous and visible plexiform neurofibromas, whereas individuals with missense mutations affecting any of the five codons 844–848 have a more severe phenotype characterized by a high prevalence of plexiform neurofibromas, optic pathway gliomas, malignant neoplasms, and skeletal abnormalities.2 This evidence concerns the gene NF1 and plexiform neurofibroma.