Quantitative trait loci for growth traits in C57BL/6J x DBA/2J mice

Quantitative trait loci (QTLs) for body weight and tail length are mapped i n an F-2 population of 927 C57BL/6J x DBA/2J mice. We test the concordance between the locations of the mapped QTLs with those detected by changes of marker frequency under artificial selection in a previous experiment with t he same base population. The directions of effects of the QTLs are generall y in agreement, and in many cases significant QTLs are found in similar map positions, but there are also discrepancies between the two experiments. T here are indications of age-specific QTL effects on growth. For body weight traits, the genetic variation in the F-2 appears to result from many loci with relatively small effects. For tail length at 10 weeks, however, a sing le QTL on Chromosome (Chr) 1 with a peak LOD score of similar to 33 contrib utes most of the genetic variation detected, changes the trait value by abo ut 6%, and explains about 20% of the phenotypic variance of the trait.