Complex I variants were frequently present at high VAFs (mean VAF = 58.8%) with IDH2 mutation in line with co-occurrence in the same tumour clone; however, when present in IDH1-mutant samples they were at lower VAF (mean VAF = 27.3%; Wilcoxon signed-rank test P value = 0.0088; Fig. 1d). The gene discussed is IDH1; the disease is neoplasm.