IDH1 and central nervous system cancer: IDH1/2 mutation (Demyashkin and Nikitin, 2018), 1p/19q codeletion (Cairncross et al., 1998), TERT promoter mutation (Arita et al., 2016) and several other markers are used to define glioma subtypes (Eckel-Passow et al., 2015).