IDH1 and glioma: Because these genetic alterations are so common, current classifications of gliomas, spearheaded by scientific discovery and adopted by the World Health Organization (WHO), have taken into account the IDH mutation status and have come up with three distinct categories of classification based on this genetic property: (1) IDH mutated with chromosome 1p/19q co-deleted; (2) IDH mutated without chromosome 1p/19q co-deleted; and (3) IDH wild-type [73].