RASA2 and neurofibromatosis type 1: Neurofibromatosis type 1 (NF1) predisposes patients to developing tumors of the nervous system.1–3 Individuals with NF1 carry loss of one functional allele of the NF1 gene encoding neurofibromin, a Ras-GTPase-activating protein (Ras-GAP) that functions as a tumor suppressor protein by negatively regulating the Ras-MAPK signaling pathway.