In addition to COGA, NIAAA has supported several other large family studies designed to identify genes contributing to the risk for alcohol dependence. These include a large study in Ireland that is recruiting siblings (Kendler et al. 1996; Prescott et al. 2005), a family study of both alcohol dependence and alcohol-related endophenotypes (including electro-physiological measures, similar to COGA) (Hill 1998), and a study of Mission Indian families (Ehlers et al. 2004). Twin studies also have remained a focus of several NIAAA-funded research projects (Jacob et al. 2001; Madden et al. 2000). Moreover, a study of offspring of alcoholic fathers has expanded into a longitudinal, multigenerational genetic study that is focused on better understanding the factors contributing to the initiation of alcohol use as well as the long-term risk for alcohol dependence (Schuckit 1991). Finally, studies also have examined African-American alcohol-dependent families ascertained on the basis of cocaine or opioid dependence (Gelernter and Kranzler 2009). Together, these approaches, although by no means completed, already have resulted in the identification of some genes that impact the risk for alcohol dependence. Some of these genes and the proteins they encode are discussed in the next section.
