COGA researchers have also analyzed candidate genes—genes suspected to play a role in the development of alcoholism based on other studies. Some of these candidate genes encode components of various brain chemical systems that allow communication among nerve cells. Two of these genes are the dopamine D2 receptor gene (DRD2) and a serotonin transporter gene (HTT). However, the analyses found no evidence that DRD2 affected the risk for alcoholism (Edenberg et al. 1998a) or that HTT was linked to either alcoholism in general or to a more severe form of alcoholism (Edenberg et al. 1998b).
