- 1 in 20,000 births.
- Increased interorbital diameter >95th percentile.
- Chromosomal defects, mainly trisomy 13, are very rare.
- Genetic syndromes are found in >50% of cases. The most common are frontonasal dysplasia (sporadic; hypertelorism, midline facial cleft, abnormalities of the nose, cranium bifidum ocultum), craniosynostosis (including Apert, Carpenter, Crouzon) and Neu-Laxova syndrome (autosomal recessive; hypertelorism, microcephaly, agenesis of corpus calosum, contractures in the upper and lower limbs, fetal growth restriction).
- Associated defects: frontal encephalocele and agenesis of the corpus calosum.
- Detailed ultrasound examination.
- Invasive testing for karyotyping and array.
- Isolated: follow-up should be standard.
- Syndromic: antenatal care should be adjusted according to the risks of the condition.
- Standard obstetric care and delivery.
- Isolated: generally good but in severe cases the cosmetic implications are important. There might be impaired stereoscopic binocular vision.
- Syndromic: generally poor with high risk of neurodevelopmental delay.
- Isolated: no increased risk of recurrence.