Data for the Genetic Analysis Workshop (GAW14) was obtained from the Collaborative Study on the Genetics of Alcoholism (COGA) [1]. Families with three or more members diagnosed with alcohol dependence were recruited from six COGA sites. Data were available from 143 pedigrees, including 1,614 family members. A subset of alcoholism phenotypes and covariates were provided. We chose the self-reported variable, "maximum number of drinks consumed in a 24-hour period," as our alcoholism phenotype. This quantitative trait is correlated with diagnosis of alcoholism and was previously shown to be linked to chromosome 4 in sibling pairs [6]. The trait was natural log transformed (lnmaxalc) to reduce skewness (2.41 vs. – 0.35) and kurtosis (12.19 vs. 2.82). Genome data included a standard 10-cM scan with 315 microsatellite markers and two SNP maps of differing densities. The Illumina Linkage III panel, referred to hereafter as SNP1, contained 4,752 SNPs with an average marker spacing of 0.78 cM. The Affymetrix GeneChip Mapping 10 K array (SNP2) contained 11,560 SNPs, averaging 0.31 cM. A total of 1,332 subjects had both microsatellite and SNP data available.
