For over 20 years, researchers here have conducted "deviant searches" at the lab, which help link specific genetic mutants to an appropriate area of research. Every two weeks, mice that differ physically or behaviorally from their littermates -- usually anywhere from five to a few dozen -- are pooled together. Jackson scientists look for mice that exhibit phenotypes (the observable characteristics of their genotypes) that are common to whatever disease or disorder they are studying, and take those mice back to their lab. This process has led to the discovery of hundreds of genes associated with genetic diseases or disorders. Some classic examples include diabetes and obesity mouse models, which led to modern-day metabolism research.