controls. These CRH and melanocortin receptor genes are thus candidates to contribute to the genetic influences on quitting success that may be independent of the genetic influences on nicotine dependence. Fifth, there are modest to moderate differences in the gender and age of nicotine-dependent vs control research volunteers studied here. While we have focused only on data from autosomal regions in these analyses and sought its replication in studies of several other addict vs control samples in ways that are likely to minimize these influences, they may not be able to eliminate them. Both nicotine-dependent and control groups are also sufficiently old to have passed through the vast majority of the ages of risk of development of nicotine dependence. Nevertheless, it is conceivable that the modest age differences in the samples studied here might have contributed modestly to some of the observed results. Sixth, in order to enhance the likelihood that the genes identified in the dependent vs control comparisons represent true positive observations, we have focused on gene variants that are also identified in other comparisons between individuals who are dependent on other substances vs controls. This strategy may reduce the novelty of the list of genes reported here,
