Modifier Selection by Transgenes: The Case of Growth Hormone Transgenesis and Hyperactive Circling Mice

Deleterious impacts of major mutations can be ameliorated by stabilising selection acting on modifier genes. We hypothesise that a new hyperactive circling mouse (counterspin: Cr) arises when modifier genes inadvertently selected to ameliorate the negative impacts of a growth hormone transgenic insertion segregate into the normal genetic background that lacks the transgene. We hypothesise that such modifiers generate a phenotype “mirror image” …