While biallelic inactivation of the NF1 tumor suppressor gene is sufficient to drive gliomagenesis of low-grade gliomas in both humans and mice [2, 27, 34], additional genetic aberrations disrupting the cell cycle and enabling telomere maintenance appear to be fundamental to the development of malignant high-grade gliomas in patients with NF1. The gene discussed is NF1; the disease is central nervous system cancer.