IDH1 and acute myeloid leukemia: Most notably we observed that maximal OCR, a surrogate for maximal mitochondrial respiratory capacity, determined after normalizing to basal OCR, was significantly lower for primary AML specimens with complex I variants (NDUFS8, NDUFS3, NDUFV2 and NDUFS1), and for those samples with IDH1 and IDH2 mutations, but not the WT group relative to healthy cells (P < 0.05, Fig. 2c, d).