In vivo cytidine base editing of hepatocytes without detectable off-target mutations in RNA and DNA

Lukas Villiger, Tanja Rothgangl, Dominik Witzigmann, Rurika Oka, Paulo J C Lin, Weihong Qi, Sharan Janjuha, Christian Berk, Femke Ringnalda, Mitchell B Beattie, Markus Stoffel, Beat Thöny, Jonathan Hall, Hubert Rehrauer, Ruben van Boxtel, Ying K Tam, Gerald Schwank

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


Base editors are RNA-programmable deaminases that enable precise single-base conversions in genomic DNA. However, off-target activity is a concern in the potential use of base editors to treat genetic diseases. Here, we report unbiased analyses of transcriptome-wide and genome-wide off-target modifications effected by cytidine base editors in the liver of mice with phenylketonuria. The intravenous delivery of intein-split cytidine base editors by dual adeno-associated viruses led to the repair of the disease-causing mutation without generating off-target mutations in the RNA and DNA of the hepatocytes. Moreover, the transient expression of a cytidine base editor mRNA and a relevant single-guide RNA intravenously delivered by lipid nanoparticles led to ~21% on-target editing and to the reversal of the disease phenotype; there were also no detectable transcriptome-wide and genome-wide off-target edits. Our findings support the feasibility of therapeutic cytidine base editing to treat genetic liver diseases.

Original languageEnglish
Pages (from-to)179-189
Number of pages11
JournalNature biomedical engineering
Issue number2
Publication statusPublished - Feb 2021


  • Adenoviridae/physiology
  • Animals
  • Cytidine/genetics
  • DNA/genetics
  • Gene Editing/methods
  • Genetic Vectors/physiology
  • HEK293 Cells
  • Hepatocytes/metabolism
  • Humans
  • Mice, Inbred C57BL
  • RNA/genetics


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