Many of the characteristic facial features result from the premature fusion of the skull bones (craniosynostosis). The head is unable to grow normally, which leads to a high prominent forehead (turribrachycephaly), and eyes that appear to bulge (proptosis) and are wide-set (hypertelorism). In addition, there is an underdeveloped upper jaw (maxillary hypoplasia). More than 50 percent of children with<unk>  have hearing loss; dental problems are also common. In people with<unk> , the thumbs and first (big) toes are wide and bend away from the other digits (pollex varus and hallux varus). Unusually short fingers and toes (brachydactyly) are also common, and there may be some webbing or fusion between the digits (syndactyly).
Pfeiffer syndrome
Zechi-Ceide syndrome
Johanson–Blizzard syndrome
Gómez–López-Hernández syndrome
Sanjad-Sakati syndrome
Adams–Nance syndrome
Lucey–Driscoll syndrome
Twiddler's syndrome