ACVR1 and diffuse intrinsic pontine glioma: A specific point mutation in one of the histone 3 genes, including H3.3 (H3F3A) or H3.1 (HIST1H3B), appears in most DIPG cases (80%) and causes lysine 27 on the amino-terminal tail to be replaced with a methionine (H3K27M).176, 177, 178 In fact, mutations in HIST1H3B resulted in a better prognosis than mutations in H3F3A. 179In addition, several genomic alterations or amplifications are observed in Tp53, activin A receptor type I (ACVR1), and platelet-derived growth factor receptor alpha (PDGFRA) in DIPGs.179