need to refine these phenotypes to obtain adequate power to demonstrate association argues against claims of robust association between DRD2/ANKK1 and alcohol dependence. These results should be considered in light of several limitations. First, the generalizability of these results may be limited as analyses were conducted using twin data from a relatively homogenous Finnish population. In addition, the relative youth of the sample is relevant. With an average age of 24.4 years, it is likely that many participants may be just entering, or have not yet aged into the period of highest risk for heavy/problem use.
