In this section, we will consider the opposite direction of translation, namely genes that are initially identified in humans, either using a candidate gene approach or as a result of a GWAS, and are then examined in mice. Although human genetics studies can be very effective in gene identification, they offer little information regarding the mechanisms by which the genes affect behavior. If the only goal of genetic studies of substance abuse was to identify markers that predict risk for substance abuse, there would be little reason to model human susceptibility alleles in mice. However, another goal of these studies is to identify the underlying biological substrates for substance use disorders. An improved understanding of the biological mechanisms is needed to design effective treatments for substance abuse. Thus, a major benefit of genetic studies in humans is the ability to perform mechanistic studies; to realize this goal, mice and other models organisms are necessary.
