Fig 4. QTL interactions with sex.

Phenotypes illustrating sex effects enhanced by a QTL on Chr 1. Males have higher body weight, body fat, and femoral circumference, and lower femoral density relative to females. The Chr 1 QTL clearly enhances these effects on femoral circumference, which is evident in the larger phenotypic effect of sex in mice homozygous for the C3H allele at the Chr 1 locus. There are smaller interaction effects for percent fat and femoral density. Importantly, the directed model for this interaction describes the results across all four phenotypes.