In this paper, we report a new case of congenital duplication of the palm syndrome (also known as limb/pelvis-hypoplasia/aplasia syndrome) and review previously reported cases and Wnt 7a gene mutations associated with that syndrome. Finally, we review the embryonic molecular events of limb development to explain the clinical features of the syndrome and to explain why the Swanson classification of duplication of the hand should be extended to include the dorsoventral duplication.