IDH-mutant astrocytomas (IMAs) are diffusely infiltrating gliomas that frequently present mutations in other genes, TP53 (in over 90% of tumors) and ATRX (in over 70% of tumors), and do not show the 1p/19q codeletion [4,5]. The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).