We focused our study on genes that have been frequently characterized by candidate gene studies. In primary analysis, over 90% of the genes associated with alcoholism in the HuGE database have 5 or fewer publications (528 out of 584 genes). The 56 candidate genes that have more than 5 publications vary substantially in the number of publications (6-103 publications). Figure 1A highlights that many genes have one or a few reported publications and there are some outliers that have been examined in many papers. This distribution may be explained in part by the fact that many of the genes with a low number of publications have been primarily identified in a GWA study and are not well characterized in targeted candidate gene studies. Figure 1B demonstrates that for almost 50% (176/386) of the genes with one publication that publication is itself a GWA study. Based on these preliminary observations, we narrowed our investigation to genes with more than 5 publications to focus our analysis on well-studied genes.
