There were 99 (8.2%) patients with GC among 1,211 adult-type diffuse glioma patients, six (3.2%) among the 190 oligodendroglioma patients, 16 (7.8%) among the 204 IDH-mutant astrocytoma patients, and 77 (9.4%) among the 817 IDH-wildtype glioblastoma patients. The gene discussed is IDH1; the disease is oligodendroglioma.