Obtaining or Generating Gene Mutations in Mice

The starting point in a mutational analysis of gene function is obtaining or producing a mutant. Here different methods of obtaining mouse mutants are discussed, including screening for spontaneous mutants, screening for mutants following chemical or X-ray mutagenesis, and producing mutations through targeted manipulation of the genome. Manipulation of the genome can be random, as in different types of insertional mutagenesis. Alternatively, targeted manipulation such as gene targeting using homologous recombination in embryonic stem (ES) cells or gene editing by CRISPR–Cas can be used to produce custom mutations in a specific gene. The basic methods are outlined, and the advantages and disadvantages of homologous recombination and CRISPR–Cas gene editing are discussed. Resources for obtaining mutations that already exist are provided. If, for your planned study, no suitable mutations are available, there is advice about what you should know about your gene of interest before embarking on a gene targeting experiment.