Phenotype

Gene knockin

Lethal allele

Biology

Gene

Gene targeting

Forward genetics

Cas9

Mutagenesis

Embryo

Mutation

CRISPR

Genetics

Gene knockout

Nature Communications

A substantial number of mouse genes, about 25%, are embryonically lethal when knocked out. Using current genetic tools, such as the CRISPR-Cas9 system, it is difficult—or even impossible—to produce viable mice with heritable embryonically lethal mutations. Here, we establish a one-step method for microinjection of CRISPR reagents into one blastomere of two-cell embryos to generate viable chimeric founder mice with a heritable embryonically lethal mutation, of either Virma or Dpm1 . By examining founder mice, we identify a phenotype and role of Virma in regulating kidney metabolism in adult mice. Additionally, we generate knockout mice with a heritable postnatally lethal mutation, of either Slc17a5 or Ctla-4 , and study its function in vivo. This one-step method provides a convenient system that rapidly generates knockout mice possessing lethal phenotypes. This allows relatively easy in vivo study of the associated genes’ functions.

Generating viable mice with heritable embryonically lethal mutations using the CRISPR-Cas9 system in two-cell embryos