IDH2 and central nervous system cancer: Moreover, recent work has shown that IDH-mutant gliomas are composed of two predominant subtypes, those with and those without 1p/19q chromosomal codeletion (IDHmut-codel and IDHmut-noncodel), with the IDHmut-noncodel subclass not only harboring the vast majority of ATRX-mutant tumors, but also exhibiting uniformly low-level ATRX expression2.