Correlation of forelimb malformation asymmetries with visceral organ situs in the transgenic mouse insertional mutation, legless.

We studied the relationship between the sidedness of visceral organs and the expression of limb abnormalities in the legless mutant. The control of asymmetry in visceral development appears to be random in the legless mutant; that is, 50% develop normally (situs solitus) and 50% develop with inverted viscera (situs inversus). We find that the sidedness of forelimb abnormalities expressed in the mutants is highly correlated with visceral sidedness. Abnormalities are more severe in the right forelimbs in situs solitus mutants, while the left forelimb is more severely affected in situs inversus mutants.