Identification and confirmation of quantitative trait loci regulating alcohol consumption in congenic strains of mice

Background: C57BL/6 inbred mice prefer alcohol whereas DBA/2 mice avoid it. We describe the construction of congenic strains of nice in which DBA/2 alleles for alcohol avoidance were placed on a C57BL/6 background using phenotypic selection. Methods: Mice were primed to drink 10% v/v ethanol in water for 2 days before a two-bottle choice paradigm. N-2 males who demonstrated an alcohol-avoidance phenotype were backcrossed to B6 females to construct 15 independent lines. Results: Eight of these lines were lost due to failure to breed or absence of males with an alcohol-avoidance phenotype. The remaining sublines were split to form a total of 21 sublines. In the N-7 and N-9 generations, a genome scan located provisional quantitative hair loci (QTLs) on chromosomes 1, 2, 3, 6, and 9. Progeny testing confirmed QTLs on chromosomes 1 and 2. Conclusions: The QTL on chromosome 2 overlaps the 95% confidence interval of Alcp1 whereas that on chromosome 1 is new and has been called Alcp5. Marker-assisted selection was used in the N-9 and subsequent generations to maintain the congenic lines and produce congenic strains.