Second, the hallmark of mitochondrial dysfunction in LHON is linked to an obvious primary dysfunction of complex I,6 whereas OPA1‐linked DOA is characterized by defective mitochondrial fusion and cristae derangement, which in turn lead to defective oxidative phosphorylation with reduced ATP synthesis driven by complex I substrates.7 Here, OPA1 is linked to Leber hereditary optic neuropathy.