A large CRISPR-induced bystander mutation causes immune dysregulation

Commun Biol. 2019 Feb 18;2:70. doi: 10.1038/s42003-019-0321-x. eCollection 2019.


A persistent concern with CRISPR-Cas9 gene editing has been the potential to generate mutations at off-target genomic sites. While CRISPR-engineering mice to delete a ~360 bp intronic enhancer, here we discovered a founder line that had marked immune dysregulation caused by a 24 kb tandem duplication of the sequence adjacent to the on-target deletion. Our results suggest unintended repair of on-target genomic cuts can cause pathogenic "bystander" mutations that escape detection by routine targeted genotyping assays.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • CRISPR-Cas Systems*
  • Cells, Cultured
  • DNA Damage
  • DNA Repair
  • Gene Duplication
  • Gene Editing / methods*
  • Gene Expression Regulation / immunology
  • Interleukin-2 Receptor alpha Subunit / genetics*
  • Interleukin-2 Receptor alpha Subunit / immunology
  • Mice, Inbred NOD
  • Mutation*
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism


  • Il2ra protein, mouse
  • Interleukin-2 Receptor alpha Subunit