In Part 1 of our mouse modeling blog series, we covered techniques that can be used to introduce genetic modifications into mouse embryos. But once you generate a growing colony of genetically engineered mice, what can you do? In this post, we’ll cover why and how to cross mice to create double knockout lines and Cre-lox lines, and how to properly control for genetically engineered mice in your experiment.
As you’ve learned in Part 1, there are many types of genetically engineered mice: transgenic mice, knockin and knockout mice, and conditional knockin or knockout mice. While these techniques are each useful for introducing one modification into the mouse genome, they are not commonly used to introduce multiple mutations. This is because as more mutations are introduced into a single embryo, the likelihood that a mouse will end up with the intended genotype at every allele decreases.