299 High efficiency and safe base editor correction of recurrent COL7A1 mutations underlying dominant dystrophic epidermolysis bullosa

Dominant dystrophic epidermolysis bullosa (DDEB) is an inherited blistering skin disease caused by heterozygous mutations in COL7A1, which encodes type VII collagen (C7), the major component of anchoring fibrils that maintain integrity dermal-epidermal junction. Most COL7A1 DDEB are single nucleotide variants, resulting glycine substitutions within C7 triple helix. Functionally, such cause impaired assembly or secretion and result dominant-negative interference through faulty wild-type mutant chains into fibrils. Adenine base editing (ABE) mediates A-T to G-C pair changes particularly suited correcting G>A mutations, account for over 60% cases. Here, we used target three most common recurrent (all exon 73) DDEB. Patient derived fibroblasts carrying either c.6082 (p.Gly2028Arg), c.6100 (p.Gly2034Arg), c.6127 (p.Gly2043Arg) were edited using ABE8e a guide RNA (sgRNA) targeting each mutation. Electroporation lipid nanoparticle delivery methods tools cells tested, with lipofection yielding higher efficiency all these mutations. Notably, achieved 100% correction mutation lipofection, no bystander present. Western blot analysis demonstrated less intracellular retention normal levels extracellular matrix, comparable fibroblasts. Base promising approach correct phenotype Using vivo compatible method editor delivery, makes results this study especially relevant future clinical translation