ABSTRACT
Obesity and type II diabetes are two of the most common complex diseases in humans that are influenced by both genetic factors and the environment. Various polygenic rodent models mimicking human obesity and type II diabetes have been developed, and these models provide valuable resources to search for genetic factors underlying the metabolic disorders. Most common forms of obesity and type II diabetes in humans, however, follow polygenic inheritances: i.e., multiple genes are involved in the development of these diseases. The Goto-Kakizaki rat strain is a model for type II diabetes without obesity. These rats were established by selective breeding for glucose intolerance from natural variations present in an outbred stock of Wistar rats. In the case of animal models, a polygenic trait can be reduced to a simpler monogenic form through the development of congenic strains in which the individual quantitative trait loci is separated as a new inbred strain on a common genetic background.
