The absence or presence of mutations in IDH1 [which encodes isocitrate dehydrogenase (NADP)] or IDH2 [which encodes isocitrate dehydrogenase (NADP), mitochondrial], and a 1p and 19q (1p/19q) chromosomal co-deletion may be important biomarkers for GBM diagnosis. Here, IDH3A is linked to glioblastoma.