In Vivo Adenine Base Editing Corrects Hutchinson - Gilford Progeria Syndrome

In vivo genome editing to correct pathogenic alleles is a promising approach to treat a wide variety of diseases with a genetic component. Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease typically caused by a single C:G-to-T:A mutation (c.1824 C-to-T, G608G) in the nuclear lamin A (LMNA) gene. This mutation activates a cryptic splice site that results in a toxic protein called progerin. Adenine base editors (ABEs) are genome editing agents that convert targeted A:T base pairs to G:C base pairs with minimal byproducts and without requiring double-strand DNA breaks or donor DNA templates. Here, we describe the use of an ABE programmed to directly correct the pathogenic LMNA c.1824 C-to-T mutation in cultured patient-derived fibroblasts and in a mouse model of HGPS. Lentiviral delivery of ABE to cultured fibroblasts leads to very efficient (approximately 90%) correction of the pathogenic allele to wild-type LMNA, mitigation of RNA mis-splicing, reduction of progerin protein levels, and correction of nuclear abnormalities. Unbiased DNA off-target editing analysis and transcriptome-wide RNA off-target editing analysis did not detect off-target activity in treated patient-derived fibroblasts. In transgenic mice expressing the causal human LMNA c.1824 C-to-T mutation, adeno-associated virus 9 (AAV9)-mediated delivery of ABE via retro-orbital injection resulted in substantial correction (approximately 20-60% in unsorted cells from a variety of organs 6 months after injection) of the pathogenic mutation, rescue of normal RNA splicing, and reduction of progerin protein. In vivo base editing of the mouse model also dramatically rescued aorta histology, preserved general animal vitality, and greatly extended animal lifespan. These findings support the potential of base editing to treat HGPS, and other genetic diseases, by directly correcting the root cause of the disease.