Thanatophoric dysplasia

**Definition:** Thanatophoric Dysplasia is a severe skeletal disorder that is lethal in the neonatal period. Two clinically defined TD subtypes have been classified: type I (TDI), characterised by micromelia with bowed femurs and, occasionally, by the presence of cloverleaf skull deformity of varying severity and type II (TDII), characterised by micromelia with straight femurs and a moderate to severe cloverleaf skull deformity.