IDH1 and central nervous system cancer: Also, the WHO CNS5 classifies tumors with alterations in H3F3A to the pediatric-type diffuse high grade gliomas family as they have significantly worse outcomes, and tumors with homozygous CDKN2A/B deletion as having the highest malignancy grade in the group of diffuse, IDH-mutant astrocytomas (135, 137).