To provide a basis for molecular genetic studies, we hypothesize that nicotine dependent participants in smoking cessation studies will display allele frequencies different from those identified in ethnically-matched control research volunteers. We postulate that we will find the most reliable results when the allele frequency differences between dependent and control individuals identify genes that we have previously identified in four prior genome wide association studies that compare allele frequencies in control individuals to those in individuals who are dependent on other abused substances. In addition, we hypothesize that successful cigarette quitters will display allele frequencies that differ from those found in ethnically-matched individuals who were unsuccessful at quitting. We thus address two research questions: 1) smokers vs non-smokers, with special interest in genes that overlap with genes identified in studies of dependence on other substances and 2) successful vs unsuccessful quitters.
