obtain highly dense SNP maps with very high information content compared with the current standard densities used in microsatellite maps for linkage analysis. To explore the utility of dense SNP maps compared with the limited number of microsatellites often available for linkage analysis, we carried out genome-wide linkage analysis of age at onset of alcoholism in the Collaborative Study on the Genetics of Alcoholism (COGA) data provided for Genetic Analysis Workshop 14 (GAW14) using 315 evenly spaced microsatellites, 2,467 Illumina SNPs, and 9,467 Affymetrix SNPs all separately spanning chromosomes 1 to 22.
