In nearly all patients with Apert syndrome, the cause is 1 of 2 FGFR2 mutations involving amino acids (Ser252Trp, Pro253Arg). The condition is inherited in an autosomal dominant mode.
Craniosynostosis is present, characterized by brachycephaly and, frequently, turricephaly; the anterior fontanelle is enlarged.
The maxilla is hypoplastic with a high-arched palate, class III malocclusion with an anterior open bite, and, frequently, a cleft of the soft palate.
The mid face is hypoplastic. This, together with the retrusion, causes exorbitism. Complex syndactyly of the hands and feet is present. It is symmetric, and other limb anomalies (eg, shortening) may be observed.
The syndactyly may show fusion of the second and forth fingernails, which also may be seen in the toes.
Typical Apert syndrome hand with syndactyly of all fingers. The thumb has been freed surgically.
Upper eyelid ptosis with an antimongoloid slant may be seen. Blindness may be present.
Overall, the deformity is worse than that of Crouzon syndrome.
The classic features of Apert syndrome, including the broad skull, bulging in the temporal area, and retrusion and vertical shortening of the maxilla.