NF1 and plexiform neurofibroma: NF1 loss of heterozygosity (LOH) in the Schwann cell lineage leads to neurofibroma development, NF1−/− melanocytes lead to café-au-lait macules and Lisch nodules, NF1−/− osteoblasts lead to pseudoarthrosis of the tibia, and NF1−/− in glial cells leads to astrocytomas.