Despite high genetic correlations, across both samples the genetic architecture is complex. A single latent genetic factor influencing all the consumption measures did not provide a good fit to the data in either sample. Rather, there are several different genetic factors that influence different measures of AC. This indicates that there is not complete overlap across measures of AC and alcohol problems, and there are different genetic influences impacting different indices of drinking. This has implications for gene identification studies in the area of alcohol dependence. It suggests that there are valid reasons why genetic findings may not “replicate” across studies that have assessed different aspects of alcohol use and dependence. In practice, this has already been seen in candidate gene studies, where genes have been associated with aspects of alcohol use, but not with alcohol dependence diagnoses (Dick et al., 2005; Foroud et al., 2007). Meta-analytic efforts that combine different indices of alcohol use and alcohol problems may enhance power to detect genetic influences that are shared across these measures, but they may miss some genetic influences specific to different aspects of alcohol use.
