IDH mutations define a subset of high-grade glioma and >80% of diffuse low-grade gliomas, of which 50-75% progress to become World Health Organization (WHO) grade IV tumors.12 Histone mutations (H3K27 and H3G34) are common in pediatric gliomas, with the H3K27M mutation found in 80% of diffuse intrinsic pontine gliomas,13 as well as in adult midline glioma. Here, IDH1 is linked to glioma.