Treacher Collins syndrome (TCS), an autosomal dominant craniofacial disorder primarily resulting from mutations in the TCOF1 gene, is characterized by hypoplasia of the zygomatic bones, mandibular deficiencies, and pronounced malformations of second pharyngeal arch-derived structures, including mimetic muscles such as ZMa and ZMi. This evidence concerns the gene TCOF1 and Treacher-Collins syndrome.