= sporadic / autosomal recessive dwarfism

Prevalence: 0.05÷10,000 births

Associated with:

1. Hydrocephalus (23%)
2. Congenital heart disease (30%): VSD, ASD, tetralogy, AS
3. Hydronephrosis (30%)

• pretibial dimple
• macrocephaly, cleft palate, micrognathia (90–99%)

• Chest & spine
  • absence / hypoplasia of scapula (92%)
  • narrow bell-shaped chest
  • hypoplastic vertebral bodies + nonmineralized pedicles (especially lower cervical spine)
• Pelvis
  • vertically narrowed iliac bones
  • vertical inclination of ischii
  • wide symphysis
  • narrow iliac bones with small wings
  • shallow acetabulum
• Extremities (lower extremity more severely affected)
  • dislocation of hips + knees
  • anterior bowing (= campto) of long bones: marked in tibia + moderate in femur
  • hypoplastic fibula
  • small secondary ossification center of knee
  • small primary ossification center of talus
  • clubfoot

OB-US:

• bowing of tibia + femur
• decreased thoracic circumference
• hypoplastic scapulae
• ± cleft palate

Prognosis: death usually <5 months of age (within first year in 97%) ← respiratory insufficiency