In keeping with this notion, mutations in the protein phosphatase Mg2+/Mn2+-dependent 1D (PPM1D) gene in pediatric gliomas also drive NAPRT gene silencing through the hypermethylation of CpG islands in the NAPRT promoter, thus, again conferring unique sensitivity to NAMPT inhibitors [54]. The gene discussed is PPM1D; the disease is glioma.