More specifically, mutations in POLR1A cause Acrofacial Dysostosis Cincinnati type (AFDCin), whereas mutations in POLR1B, POLR1C and POLR1D and the Pol I associated protein, TCOF1/TREACLE lead to Treacher Collins Syndrome (TCS) [21–25]. This evidence concerns the gene POLR1D and acrofacial dysostosis Cincinnati type.