IDH1 and glioma: Oligodendrogliomas (ODGs) are defined as gliomas with a mutation in IDH1/2 genes and an unbalanced translocation between chromosomes 1 and 19 (1p/19q-codeletion); they are graded on a scale of 2–3, based upon histological features such as mitotic activity and presence of microvascular proliferation or necrosis [27].