COGA data provided by GAW14 include 143 pedigrees with 1,614 individuals genotyped with both microsatellites and SNPs. In addition, the genetic maps for both the microsatellites and the SNPs were provided. We used the nonparametric linkage analysis implemented in MERLIN [3] for linkage analysis. Individuals were defined as unaffected with alcoholism if they never drank alcohol or if they showed some alcohol-related syndromes but did not meet the criteria for alcoholism [4]. Allele frequencies were estimated using all genotyped individuals, and the Whittemore and Halpern "ALL" statistic [5] was applied for the scan procedure, in which the NPL scores based on all affected pedigree members were calculated. Both the SNP scan and the microsatellite scan were performed at each marker locus.
