Genome scan linkage mapping projects have identified promising map positions for AD susceptibility loci, some of which have already led to the discovery of disease-influencing genes. The first linkage studies of AD (6–8) provided nonsignificant support for several chromosomal locations that could potentially harbor loci influencing risk. Wilhelmsen et al. (9) reported a genomewide linkage study for an alcohol-related trait, low-level response to alcohol; although this study considered a small sample (139 sibling pairs), several “suggestive” linkages were identified. Ehlers et al. (10) conducted linkage analysis in a sample of Mission Indians; several lod scores >2 were identified for the phenotypes of alcohol severity (chromosomes 4 and 12) and alcohol withdrawal (chromosomes 6, 15, and 16). The most recent large study to be reported focused on a set of 474 small families recruited in Ireland (11); this study also reported strongest results (up to a genomewide-significant multipoint lod score of 4.59) on chromosome 4. We are not aware of any previous linkage study that focused on AD in an AA population.
