Gli3 expression is affected in the morphogenetic mouse mutants add and Xt.

We investigated the relation between the recessive mutation add caused by insertional mutagenesis of a transgene and the dominant mutation extra-toes (Xt) which display similar effects on limb morphogenesis. The transgene insertion in add mapped close to the 5' end of the zinc finger gene Gli3 and 5'sequences of Gli3 were deleted in Xt. Expression analysis revealed a reduction of the Gli3 RNA level in both add and Xt mice. Thus, it is very likely that add and Xt are alleles of the Gli3 gene.