Osteogenesis imperfecta (OI) is a skeletal dyscrasia characterized by decreased bone strength and associated fractures. Over 95% of autosomal dominant forms of this disease are associated with defects in the genes for collagen COL1A1 and COL1A2.1 The lethal type II disease has been identified antenatally by symmetrically shortened long bones and micromelia. Many reports have indicated that a femur length to abdominal circumference ratio (FL:AC) of less than 0.16 is predictive of lethality associated with OI.2,3 We report a case that presented at 20 weeks’ gestation with shortening of the lower limbs, specifically a lagging femur length and FL:AC of < 0.16. On subsequent ultrasound examinations, progressive shortening of the femur as well as shortening of the long bones of the upper extremities was documented. The thorax appeared normal until 31 weeks. The FL:AC remained below 0.16 throughout pregnancy. Workup in the neonatal period identified a novel mutation in COL1A1. The neonate was able to breathe spontaneously at birth requiring minimal respiratory support for the initial 2 weeks and lived for 26 days.
Osteogenesis imperfecta, mutation, collagen, femur length
The authors report no conflict of interest.
Copyright © 2014 Sarah A. Wernimont, Vani C. Movva, and Asha Rijhsinghani
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