We transfected 293T cells with the MT-ND4.2 DdCBE (hereafter LHON DdCBE) to install a missense mutation in the MT-ND4 gene associated with Leber’s hereditary optic neuropathy (LHON), then sorted cells based on their intensity of eGFP and mCherry fluorescence (Extended Data Fig. 2c) and performed SCI-LITE. The gene discussed is MT-ND4; the disease is Leber hereditary optic neuropathy.