In GS deficiency, glutamine deficiency results in reduced NAD+ synthesis, which plays an important role in redox reactions.6 In GLS hyperactivity, glutamate excess is postulated to decrease redox buffer capacity.19 As oxidative stress is associated with cataract, neurodegenerative disorders and epilepsy, this is a likely key player in the pathophysiology of these inborn errors of glutamate metabolism.10, 20, 88. Here, GLS is linked to epilepsy.