Clinical Presentation

A 16-month-old child presents with hypertelorism, an elongated, flattened forehead, and syndactyly of hands and feet.

Figure 115A

Figure 115B

Figure 115C

Radiologic Findings

Diagnosis

Apert syndrome (acrocephalosyndactyly type 1)

Differential Diagnosis

• Carpenter syndrome
  
• Pfeiffer syndrome
  
• Saethre-Chotzen syndrome
  
• Crouzon syndrome
  
• Rubinstein-Taybi syndrome
  
• Amniotic band syndrome
  
• Isolated familial syndactyly syndromes

Discussion

Background

Many syndromes and conditions include abnormalities of both the craniofacial structures and the limbs. Patients with syndactyly, distal limb abnormalities, and craniosynotosis most often suffer from acrocephalosyndactyly. Of the specific entities within this grouping, Apert syndrome is the most common. The association between syndactyly and craniosynostosis was first described by Apert in 1906.

Etiology

Apert syndrome shows autosomal dominant heritance, but nearly all cases result from new gene mutations. The incidence of Apert syndrome in the general population is ~1 in 160,000 live births.

Apert syndrome appears to be caused by either of two distinct point mutations in fibroblast growth factor receptor 2 (FGFR2). Close phenotypic mimics are Crouzon syndrome and Pfeiffer syndrome, both of which are also caused by mutations in FGFR2.

Clinical Findings

Apert syndrome may be diagnosed prenatally and presents clinically at birth. Cranial findings seen in affected infants include a flattened, elongated forehead, turribrachycephaly, hypertelorism, exophthalmos, a bulbous nose, and a flattened nasal bridge. Nasopharyngeal obstruction is seen in 50%, due to midface hypoplasia. The orbits show downward slanting. Most patients demonstrate at least mild prognathism.