IDH1 and glioma: The novel stratification of glioma with 1p/19q co-deletion based on fluorescence in situ hybridization (FISH) analysis and IDH mutant or wildtype based on IHC analysis became more sophisticated with additional diagnostic evaluation indices such as loss of ATRX expression or TERT promoter mutations, the presence of TP53 or histone H3 mutations, EGFR amplification, and CDKN2A/B alterations [16].