Identifying genes for alcohol and drug sensitivity: recent progress and future directions

New methods for identifying chromosomal regions containing genes that affec t murine responses to alcohol and drugs have been used to identify many pro visional quantitative trait loci (QTLs) since 1991. By 1998, 24 QTLs had be en definitively mapped (P<5 x 10(-5)) to specific murine chromosomes, which indicates the presence of a relevant gene or genes at each location. The s yntenic (homologous) region of the human genome for these genes is often kn own. For many mapped QTLs, candidate genes with relevant neurobiological fu nction lie within the mapped region. Data that implicate candidate genes fo r specific responses include studies of knockout animals. Current strategie s for gene identification include the use of congenic strains containing QT L regions introduced from another strain. There is increasing emphasis on g ene-gene and gene-environment interactions in such studies.