Matrix assisted laser desorption/ionization - time-of-flight analyses detected r-2HG within the 0.8–11 mM range in 4-μm frozen slices of brain tumors containing IDH1/2 mutations, whereas 0.2–0.4 mMr-2HG was detected in wt tumor tissue slices (97). This evidence concerns the gene IDH1 and neoplasm.