Mapping of quantitative trait loci with knockout/congenic strains

Recently we have explored the use of knockout/congenic mouse strains for is olating and mapping quantitative trait loci (QTLs). Because most knockout s trains have been bred to be B6.129 congenic strains, they can be used to te st for QTLs in the targeted chromosomal area as Iona as there is a genetic difference between B6 and 129. Thus, we have tested a number of knockout/co ngenic strains in a series of behavioral tests in which mouse performance h as a slanificant genetic component. We have also developed a breeding schem e for distinguishing the effects of background flanking genes from the targ eted ablation. In screening several knockout/congenics, we have found at le ast one that harbors a behavioral QTL in the 129 chromosomal segment. The p osition of this QTL was confirmed Subsequently by several A crosses.