A Respiratory chain enzyme activities from human control (green) and patient (red) fibroblasts. Mean activities of controls (n = 8) are set to 100% and error bars represent 1 standard deviation. Data are normalised to citrate synthase (CS) activity. B Respiratory chain enzyme activities in heart, brain and liver, of wild-type and Uqcrh-/- mice. Data are normalised to citrate synthase (CS) activity. Values are given as mean ± SD, n = 4 WT, 5 Uqcrh-/- (Heart), 3 WT, 3 Uqcrh-/- (Brain), 1 WT and 2 Uqcrh-/- (Liver). * p < 0.05, **** p < 0.0001, 2-way ANOVA (Multiple comparison). 