The differences observed between astrocytomas, IDH-mutant, and oligodendroglioma were very similar to those observed between astrocytomas, IDH-wild-type, and oligodendroglioma with oligodendroglioma intensities having the most significant differences at peaks assigned to phenylalanine (1003 cm–1 and 1036 cm–1), DNA (881 cm–1, 885 cm–1, and 1342 cm-–1), and protein (1522 cm–1 and 1551 cm–1). Here, IDH1 is linked to oligodendroglioma.