OPA1 and Leber hereditary optic neuropathy: In OPA1−/− human primary neuronal cultures, excessive fragmentation and overactive mitophagy was found to be a possible mechanism of progressive optic atrophy in individuals with OPA1 mutations, and mitophagy is robustly increased in Leigh/Leber hereditary optic neuropathy patient-derived fibroblasts (Dombi et al., 2016; Liao et al., 2017).