The frontal cortex from multiple patients with Alpers’ syndrome demonstrated increased GFAP + labelling relative to the control group (Supplementary Fig. 4a however, this was frequently less severe compared to the occipital cortex (Supplementary Fig. 4b), and frontal astrocytes were frequently significantly smaller than occipital astrocytes (Supplementary Fig. 5). Here, GFAP is linked to Alpers syndrome.