of a recipient background strain. Narrowing the QTL interval to a small region (~1-2 Mb) also substantially reduces the number of potential candidate genes remaining within the finely mapped interval. A data base is available that summarizes these alcohol related QTLs, as well as additional significant (and suggestive) QTLs for a variety of ethanol response traits, and information about the size of the confidence interval surrounding the QTL and/or its definitive limits derived from subsequent analyses with congenic strains from fine mapping studies (http://www.ohsu.edu/parc/data/qtl/by_phen.shtml). QTL fine-mapping has been crucial to reduce the number of potential candidate genes within the QTL interval and, when coupled with detailed molecular analyses of candidate gene allelic variation in sequence and/or expression, has been key to identifying high-quality quantitative trait gene [QTG] candidates. In at least one case, studies have actually identified a QTG for alcohol withdrawal severity, i.e., Mpdz, which encodes the multi-PDZ domain protein (MPDZ, also called MUPP1) (see Shirley et al., 2004).
