The results of these follow-up and exploratory analyses are not surprising given that alcohol dependence is hypothesized to represent a multi-faceted disorder that is likely due to the convergence of partially distinct biological mechanisms (e.g., sensitivity to alcohol and personality characteristics related to addiction), which may be measured to differing degrees by each of the DSM-IV alcohol dependence symptoms (Schuckit, 1994). While it is important to emphasize that these analyses were conducted in an exploratory manner thus requiring replication before substantive conclusions can be made, these findings provide an important illustration of how a subset of symptoms may show increased evidence for linkage relative to the overarching diagnostic category. As a result, it is an important empirical question to ask which collection of symptoms within a diagnosis is responsible for the observed genetic linkage or association. This approach to linkage analysis of alcohol dependence was previously utilized by Prescott et al. (2006), and together with the findings reported herein, provide important insights for future studies seeking to further our understanding of the genetic influences underlying alcohol dependence.
