QTL interaction with IGF1.

The effects of IGF1 are enhanced by QTL 9.2. IGF1 has a small positive effect on each phenotype in animals homozygous for the B6 allele at this locus. This can be seen in the positive slope of the blue line in each panel, which shows that each phenotype increases with increasing levels of IGF1. The effect of IGF1 on all phenotypes except femoral density is enhanced in heterozygotes (green line) and enhanced further in C3H homozygotes (purple line). For these genotypes, the increase in slope indicates that there is a more pronounced increase in phenotype as IGF1 levels increase. Y-axes represent rank normalized values of each phenotype, and x-axes represent rank normalized IGF1 levels scaled to range between 0 and 1. Shaded regions show 95% confidence interval for each slope.