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Nat Med. 2018 Oct;24(10):1519-1525. doi: 10.1038/s41591-018-0209-1. Epub 2018 Oct 8.

Treatment of a metabolic liver disease by in vivo genome base editing in adult mice.

Author information

1
Department Biology, Institute for Molecular Health Sciences, ETH Zurich, Zurich, Switzerland.
2
Division of Metabolism, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland.
3
SIB Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland.
4
Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.
5
Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.
6
Swiss Newborn Screening Laboratory, University Children's Hospital, Zurich, Switzerland.
7
Zurich Center for Integrative Human Physiology, Zurich, Switzerland.
8
Neuroscience Center Zurich, Zurich, Switzerland.
9
Department Biology, Institute for Molecular Health Sciences, ETH Zurich, Zurich, Switzerland. schwankg@ethz.ch.

Abstract

CRISPR-Cas-based genome editing holds great promise for targeting genetic disorders, including inborn errors of hepatocyte metabolism. Precise correction of disease-causing mutations in adult tissues in vivo, however, is challenging. It requires repair of Cas9-induced double-stranded DNA (dsDNA) breaks by homology-directed mechanisms, which are highly inefficient in nondividing cells. Here we corrected the disease phenotype of adult phenylalanine hydroxylase (Pah)enu2 mice, a model for the human autosomal recessive liver disease phenylketonuria (PKU)1, using recently developed CRISPR-Cas-associated base editors2-4. These systems enable conversion of C∙G to T∙A base pairs and vice versa, independent of dsDNA break formation and homology-directed repair (HDR). We engineered and validated an intein-split base editor, which allows splitting of the fusion protein into two parts, thereby circumventing the limited cargo capacity of adeno-associated virus (AAV) vectors. Intravenous injection of AAV-base editor systems resulted in Pahenu2 gene correction rates that restored physiological blood phenylalanine (L-Phe) levels below 120 µmol/l [5]. We observed mRNA correction rates up to 63%, restoration of phenylalanine hydroxylase (PAH) enzyme activity, and reversion of the light fur phenotype in Pahenu2 mice. Our findings suggest that targeting genetic diseases in vivo using AAV-mediated delivery of base-editing agents is feasible, demonstrating potential for therapeutic application.

Comment in

PMID:
30297904
DOI:
10.1038/s41591-018-0209-1
[Indexed for MEDLINE]

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