Crouzon syndrome in a fraternal twin: A case report and review of the literature

Table 1 Clinical characteristics of the most common syndromic craniosynostosis syndromes

	Crouzon	Apert	Pfeiffer	Muenke	Saethre-Chotzen
Gene	FGFR2	FGFR2	FGFR1/ FGFR2	FGFR3	TWIST1
Craniofacial phenotype	Brachycephaly; shallow orbits; ocular proptosis; midface hypoplasia	Turribrachycephaly; large anterior fontanelle with bitemporal widening and occipital flattening; shallow orbits with ocular proptosis and horizontal grooves above supraorbital ridges; mild hypertelorism and down-slanting palpebral fissures; “parrot beak” nasal deformity	Turribrachycephaly; midface hypoplasia; proptosis; hypertelorism; strabismus; down-slanting palpebral fissures; beaked nasal deformity	Craniosynostosis of coronal sutures; uncommon to have midface hypoplasia	Brachycephaly or acrocephaly or anterior plagiocephaly; low frontal hairline; eyelid ptosis; facial asymmetry; deviated nasal septum; ear deformities; parietal foramina
Oral and dental phenotype	Constricted, high-arched palate; anterior open bite; Missing teeth; supernumerary; delayed tooth eruption	High arched or cleft palate; severe midface hypoplasia; anterior open bite; tooth agenesis; supernumerary teeth; dental fusion; delayed tooth eruption	Anterior open bit and bilateral posterior cross-bites; hypodontia; microdontia; dilacerations; radicular dentin dysplasia	High arched palate; the lowest incidence of cleft palate	Cleft palate
Limb phenotype	Normal hands and feet	Severe syndactyly (mitten hand); poor joint mobility	Broad thumbs; broad great toes; variable feature, partial soft-tissue syndactyly of the hands; ankylosed elbows; hydrocephalus	Thimble-like middle phalanges	Brachydactyly; syndactyly; radioulnar synostosis; Hallux valgus
Other phenotype		Low-set ears	Hearing loss; visceral anomalies	Hearing loss	Hearing loss; congenital heart malformation; short stature
Cognition	Normal	Intellectual disability	Normal or nearly normal		Normal

FGFR: Fibroblast growth factor receptor.