The focus of this study was discovery of allelic associations for DSM-IV defined nicotine and alcohol dependence in unrelated individuals using a case-control pooling design (Risch & Merikangas, 1996; Sham et al., 2002). Information was collected using a computer-assisted telephone diagnostic interview (CATI). Self-reported symptoms of DSM-IIIR and DSM-IV alcohol dependence and quantity and frequency of alcohol consumption were measured using an adaptation of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) (Bucholz et al., 1994) for telephone administration. The tobacco section for the CATI was derived from the Composite International Diagnostic Interview (CIDI) (Cottler et al., 1991), and incorporated the Fagerstrom Test for Nicotine Dependence (FTND) (Heatherton et al., 1991) and DSM-IIIR and DSM-IV assessments of nicotine dependence. For the purposes of this study, nicotine (ND) and alcohol dependent (AD) cases were defined using DSM-IV criteria. ND controls were defined as individuals exposed to smoking (all AD−/ND− subjects tried cigarettes at some point in their lifetime; see Table 1), but had never become dependent. Similarly, all AD controls were exposed to cigarettes and practically all to alcohol (99%
