IDH1 and glioma: Lower-grade gliomas with both an IDH mutation (i.e., a mutation in either IDH1 or IDH2 and deletion of chromosome arms 1p and 19q (1p/19q codeletion), which occurs most often in oligodendrogliomas, have better responses to radiochemotherapy and are associated with longer survival than diffuse gliomas without these alterations [10].