Abstract: The present invention relates to a method for testing genome editing in a cell-free, in vitro system and, in particular, to a method for identifying and quantifying target DNA mutations by a base editor without using eukaryotic cells and without separate complicated experimental procedures. By using the present invention, target DNA mutations can be identified and quantified by a base editor without using cells and without separate complicated experimental procedures. In addition, a base editor having the ability to edit target DNA mutations in actual cells can be screened through a simple cell-free test method.

Abstract: Described herein is a base editing system for correcting mutations G3460A, G11778A, or T14484C in mitochondrial DNA of a patient with Leber hereditary optic neuropathy (LHON) to a normal genotype. Also, described herein is a method for correcting a mutation in the mitochondrial genes of a patient with LHON to a normal genotype using a base editor that recognizes specific sites in the mitochondrial genes of the patient with LHON and has an activity of specifically correcting the adenine base at position 3460 or 11778, or the cytosine base at position 14484, by using a fusion protein or a polynucleotide encoding such a fusion protein. The base editor or nucleotide described herein may correct DNA mutations specific to LHON in a cellular or extracellular in vitro environment. Thus, described herein is also the use of the substance in the prevention or treatment of LHON.