thanatophoric dysplasia

Thanatophoric dysplasia is a lethal skeletal dysplasia. It is the most common lethal skeletal dysplasia followed by osteogenesis imperfecta type II.


The estimated incidence is around 1:25,000-50,000 .



It results from a mutation coding for the fibroblast growth receptor 3 (FGFR3) located on chromosome 4p16.3. The type of receptor mutation is different from the FGFR mutation in achondroplasia. Inheritance is thought to be sporadic.


There are two recognized subtypes:

  • type I: marked underdevelopment of skeleton, telephone handle femurs more pronounced
  • type II
    • the presence of a cloverleaf skull may be a distinctive feature
    • limb shortening milder and bowing is not a feature

Radiographic features

Antenatal ultrasound

It may be difficult to accurately diagnose before the 3 trimester (≈22 weeks) . Before that time it can be included in the differential if there is a short femur length measurement.

Sonographically-detectable features may include:

  • relatively narrow thoracic cavity
  • short, thick, bowed tubular bones, especially lower extremity
  • thickened soft tissues of extremities
  • comparatively large head with frontal bossing 
  • a cloverleaf skull appearance may also be seen: type II (see case 3)
Plain radiograph 

Plain films are usually done postmortem, if done at all. Features include:

Iliac bones
  • narrow chest
  • short horizontal ribs
  • small scapulae
Skull and face
  • platyspondyly: flattening of vertebral bodies
  • normal trunk length

Treatment and prognosis

The condition is uniformly fatal within a few hours of birth either from respiratory failure or from brainstem compression from a narrow foramen magnum.

History and etymology

The term thanatophoric derives from the Greek words "thanatos" (θάνατος) meaning "death"  and "phoros" meaning "bearing/carrying/bringing".

See also

Siehe auch:
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