IDH1 and low grade glioma: Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2), mainly Arg132 for IDH1 and Arg140 and Arg172 for IDH2, occur in over 80% of low-grade glioma (LGG) (Parsons et al., 2008; Watanabe et al., 2009; Yang et al., 2012; Cancer Genome Atlas Research Network et al., 2015; Suzuki et al., 2015).