- lethal metatropic dysplasia (type 2) or hyperchondrogenesis
- lethal hyperplastic metatropic dysplasia (type 1)
- Schneckenbecken dysplasia
Post-natal clinical findings include a narrow chest and shortened extremities with a coccygeal tail seen in some cases. Joint contractures and kyphosciolosis can manifest within the first year of life. As the kyphoscoliosis worsens with time, eventually patients can have a comparably short appearing torso when compared to the limbs, despite associated limb shortening.
Characteristic radiological features include:
- short diaphyses with a wide 'mushroom' shape metaphyses (dumbell shape)
- narrow sacrosciatic notches
- delayed ischio-pubic mineralisation
- severe platyspondyly
- thin dense vertebral bodies
History and etymology
The term 'metatropic' originates from the Greek 'metatropos - μετατροπος' which means 'changing patterns'. This name has been given in light of the fact that the skeletal phenotypes of this group of dysplasias change with time as patients age.
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