To examine whether Alk might be involved in the expression of ethanol-related behaviors, complementary database approaches similar to those described in Lu et al. were employed [50]. First, the genotypes of the BXD recombinant inbred (RI) strains at a marker in the Alk locus, rs4137129, were tested for associations with ethanol-related behaviors in GeneNetwork (www.genenetwork.org). Genotypic differences in the expression of the behavior were considered significant at P<0.05 by uncorrected t-tests for the comparison of C57BL/6J and DBA/2J genotype. Second, variation in Alk expression in multiple brain regions, including the whole brain [51], cerebellum, hippocampus [52], neocortex [53], nucleus accumbens, prefrontal cortex, and striatum, was examined for correlations with RI strain means for all of the available behaviors in GeneNetwork. We used a cutoff of |r|≥0.5 to identify potentially meaningful correlations between Alk expression and behavior. The traits identified by both techniques were then combined, resulting in a list of traits that differed as a function of genotype at the Alk locus and were associated with variation in Alk expression in at least one brain region.
