Journal of Heredity Advance Access published online on June 5, 2008
Journal of Heredity, doi:10.1093/jhered/esn045
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An Epistatic Genetic Basis for Physical Activity Traits in Mice
From the Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223 (Leamy); the Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, NC 28223 (Lightfoot); and the Department of Nutrition, University of North Carolina, Chapel Hill, NC 27599 (Pomp); Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599 (Pomp); and the Carolina Center for Genome Science, University of North Carolina, Chapel Hill, NC 27599 (Pomp)
Address correspondence to L. J. Leamy at the address above, or e-mail: ljleamy{at}uncc.edu.
We recently identified several (4–8) quantitative trait loci (QTL) for 3 physical activity traits (daily distance, duration, and speed voluntarily run) in an F2 population of mice derived from an original intercross of 2 strains that exhibited large differences in activity. These QTL cumulatively explained from 11% to 34% of the variation in these traits, but this was considerably less than their total genetic variability estimated from differences among inbred strains. We therefore decided to test whether epistatic interactions might account for additional genetic variation in these traits in this same population of mice. We conducted a full genome epistasis scan for all possible interactions of QTL between each pair of 20 chromosomes. The results of this scan revealed an abundance of epistasis, with QTL throughout the genome being involved in significant interactions. Overall, epistatic effects contributed an average of 26% of the total variation among the 3 activity traits. These results suggest that epistatic interactions of genes may play as important a role in the genetic architecture of physical activity traits as single-locus effects and need to be considered in future candidate gene identification studies.
Corresponding Editor: Roger H. Reeves
Received January 24, 2008
Accepted April 24, 2008