To identify existing genomewide linkage studies on smoking behavior, we conducted a computerized literature search of the PubMed database using the following keywords and subject terms: ‘linkage’, ‘smoking’, ‘nicotine dependence’, ‘genome-wide’, or ‘genomewide’. Review articles on genetics of smoking behavior were also screened. The genome scans included in the current GSMA were required to meet the following criteria: 1) whole genome linkage scan on smoking related traits performed in humans; 2) whole genome linkage results either available from the original investigators, or extractable from published graphs; 3) samples used in genome scans should be independent of each other. Linkage studies which were repeated analyses of the same sample using different statistical methods or phenotype measures were identified, and we included only one independent study for which the whole genome linkage results were available. In addition, when a study reported whole genome linkage results on different samples; we treated each sample as a separate genome scan. When a study reported a two-stage analysis, only the original results were used and any follow up studies in candidate regions were excluded, as the GSMA requires a uniform distribution of markers across the genome (25).
