Which syndrome is defined by craniosynostosis, maxillary hypoplasia, and symmetric syndactyly?

• A. Pfeiffer syndrome
• B. Crouzon syndrome
• C. Apert syndrome
• D. Saethre-Chotzen syndrome

Answer: (C)

Recognizing patterns of craniosynostosis with limb anomalies helps differentiate these syndromes. The combination of craniosynostosis, maxillary hypoplasia, and symmetric syndactyly is the hallmark of Apert syndrome. An activating FGFR2 mutation drives premature skull suture fusion and midface underdevelopment, while the same process causes the fingers and toes to fuse in a symmetric, prominent way. Other syndromes may share craniosynostosis or facial features but lack the characteristic symmetric syndactyly: Pfeiffer typically shows broad thumbs and toes rather than true, symmetric digit fusion; Crouzon has craniosynostosis with midface hypoplasia but usually no syndactyly; Saethre-Chotzen can have mild, often asymmetric syndactyly along with craniosynostosis. So the described triad best fits Apert syndrome.