Both genotype and phenotype data were available for 1647 individuals, and phenotype but not genotype data were available for 875 individuals. Participants not genotyped included relatives of genotyped probands that did not provide DNA samples and probands and their relatives not belonging to a genetically informative pedigree. Notably, rates of alcohol and nicotine dependence remained unchanged when participants not genotyped were removed from the sample (data not shown). Seven hundred and thirteen families that contained sibling, half-sibling, avuncular or cousin pairs were considered genetically informative for linkage analysis. These families ranged in size from 3 to 20 subjects (average 4.63±2.13). The data includes: 1085 sibling, 40 half sibling, 17 grandparent-grandchild, 238 avuncular, and 32 cousin relative pairs. An additional 177 families contained only a single individual with phenotype data. These individuals were included within some analyses to the extent that they contribute information about trait means and variance and the impact of covariates.
