IDH1 and brain stem glioma: A couple of studies have shown that mutations in IDH1 and IDH2 genes can be found in 18-31% of adult brainstem gliomas (18–20) and that a majority of these mutations are non-canonical IDH1/2-mutations (21, 22), compared to a high frequency of IDH1 R132H mutations in IDH-mutant supratentorial diffuse gliomas (23, 24).