At the group level, calretinin+ interneurons from patients with Alpers' syndrome harboured a significantly higher mean optical intensity of porin relative to control interneurons (P < 0.001) (supporting information Figure S4); however, mean patient porin z‐scores were mostly within the normal range (z < 2) indicating normal mitochondrial mass (supporting information Figure S5). This evidence concerns the gene VDAC1 and Alpers syndrome.