IDH1 and central nervous system cancer: In glioma, the mutations occur at the arginine residue at codon 132 in IDH1 (IDH1R132H) and at codon 140 in IDH2, and since the IDH1R132H alteration accounts for 90% of IDH mutations, immunohistochemistry (IHC) evaluation with an IDH1R132H antibody can cover 90% cases of IDH1/2 mutation [6].