GLI3 mutations lead to a variety of clinical phenotypes, such as Greig cephalopolysyndactyly syndrome (GCPS, OMIM175700), Pallister–Hall syndrome (PHS, OMIM146510), Acrocallosal syndrome (ACLS, OMIM200990), preaxial polydactyly type IV (PPD4, OMIM174700), and postaxial polydactyly type A (PAPA1, OMIM174200) (Shin, Kogerman, Lindstrom, Toftgard, & Biesecker, 1999). The gene discussed is GLI3; the disease is polysyndactyly 4.