GLI3 and Greig cephalopolysyndactyly syndrome: Loss-of-function variants in GLI3 can lead to various limb development disorders, including Greig cephalopolysyndactyly syndrome (GCPS; OMIM 175,700), preaxial polydactyly type A/B (PAPA/PAPB; OMIM 174,200), Pallister Hall syndrome (PHS; OMIM 146,510), postaxial polydactyly type A1 and B (OMIM 174,200) and preaxial polydactyly type III (OMIM 174,700) [17–20].