IDH1 and diffuse astrocytoma: According to the 2016 revision of the World Health Organization (WHO) classification of tumors of the central nervous system, the major pathological types of grade 2 low-grade gliomas (LGGs) include diffuse astrocytomas (wild-type IDH1, mutant IDH1, or not otherwise specified) and oligodendrogliomas (mutant IDH1 and 1p/19q co-deletion or not otherwise specified) [2].