Overview of designing genetically engineered mouse (GEM) models

It is very important to spend time and effort on vector design considerations when planning to make a GEM. The vector designer will ask what information is desired from the genetically modified animal, and an engineering scheme will be devised. It is strongly recommended that the investigator consult experienced GEM vector producers with all the information that is desired from the GEM. The investigator will be apprised of the feasibility of each design consideration, and usually learns of additional design elements that may expand the information that can be obtained from the GEM and that can in turn expand the overall research yield. Our experience is that the extra time, effort, and care that is put into the coordination of GEM design with research objectives saves much time and effort in the long run. In addition, we have found that careful GEM design consideration will greatly improve the success of GEM production. In this chapter, we discuss gene targeting design considerations that should be made before initiating production of the engineered mouse strain.