Duplication of the leg--renal agenesis: congenital malformation syndrome.

A case is given of a male born with a duplication of the left leg and ipsilateral kidney agenesis. Although the etiology is unknown, we believe this association represents a congenital malformation syndrome. It is a polytopic developmental field defect. The growth factor IGF-I produced by the intermediary mesoderm or mesonephros (embryonary kidney) could be implicated in the induction limb development and the application of FGF-8 protein to the flank of young chick embryos inducing the development of additional limbs. It is possible that one or more of the growth factors produced by the mesonephros take some cells of the intermediary mesoderm out of their renal way to form a supernumerary limb.