File:12967 2022 3685 Fig4 HTML (1).webp

English: Multiple GT approaches for the treatment of MD. Existing approaches enable targeting both nuclear(n) or mitochondrial(mt) DNA. In general, possible interventions may be divided into the following strategies: (1) Reparation of mutant genes (including base edition); (2) Elimination of mutant mtDNA; (3) Replacement (including allotopic expression).1. Reparation of mutant nuclear genes can be performed with the use of programmed nucleases (TALEN, ZFN, CRISPR/Cas). A modified version of CRISPR (CRISPR-deaminase) can be utilized for base edition (introduction of single nucleotide substitutions) in nuclear genome whereas modified version of TALEN (TALEN-deaminase) can be utilized for base edition in the mitochondrial genome. 2. In order to eliminate mutant mtDNA, double-stranded breaks induced by programmable nucleases TALEN, ZFN, CRISPR/Cas, can be used. Another option is application of antireplicative machines FD-RNA or peptide nucleic acids (PNA).3. The function of altered gene may also be compensated by its wild type copy delivered into mitochondria or nucleus. In the case of replacement of mitochondrial genes, sequence can be allotopically expressed in the nucleus, but only after reprogramming in mitochondrial genetic code and appending mitochondrial-targeting sequence