According to the current WHO classification astrocytomas and oligodendrogliomas are defined as IDH1/2 mutant tumors, with the exemption of circumscribed gliomas that include entities like pilocytic astrocytoma and pleomorphic xanthoastrocytoma as well as pediatric type gliomas [1]. The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).