Mutations in the human transcription factor GLI3 cause a variety of dominant developmental defect syndromes, subsumed under the term “GLI3 morphopathies” [1], including Greig cephalopolysyndactyly syndrome (GCPS) [2]–[4], Pallister-Hall syndrome (PHS) [5], postaxial polydactyly type A (PAPA) [6], and preaxial polydactyly type IV (PPD-IV) [1]]. This evidence concerns the gene GLI3 and polysyndactyly 4.