Similar to the occipital cortex, the expression of glutamine synthetase was variable in frontal cortical astrocytes in the Alpers’ syndrome patient group involving a decreased intensity in four of seven patients with Alpers’ syndrome (P < 0.01) and increased intensity in one patient relative to control group (P < 0.0001) (Supplementary Fig. 7). The gene discussed is GLUL; the disease is Alpers syndrome.