Quick method for confirmation of quantitative trait loci

Numerous algorithms for the identification and genetic mapping of quantitative trait loci (QTL) have been developed. Methods for confirming QTL maps involve either examination of independent segregating populations or the construction of congenic lines differing only in the QTL of interest. Because these projects require a minimum of several years or thousands of marker assessments in laboratory mice, an alternative, faster congenic method has been proposed. In a preliminary study, we tested this method for confirming QTLs identified in crosses between the ILS and ISS selected lines of mice for differential sensitivity to the hypnotic effects of ethanol. Herein, we report the construction of "segregating congenic" strains in which each QTL is made homozygous in a single generation, whereas the remainder of the genetic background is allowed to segregate. Sensitivity to ethanol among the progeny of such mice is consistent with predictions. Phenotypic variation is high, as expected, due to the background segregation, and statistical significance was attained in only 2 of 7 comparisons. Such segregating congenic populations may be a valuable research tool for confirming QTL map positions and for subsequent assessment of individual pathways and mechanisms of action of individual QTLs.