The Nicholas Andry Award-1996. The molecular pathology of osteogenesis imperfecta.

A systematic analysis of the molecular pathology of osteogenesis imperfecta was undertaken in 200 cases. The findings indicate that molecular defects of Type I collagen are the major cause of this disease. The mild form of osteogenesis imperfecta is caused by quantitative anomalies of Type I collagen. The other forms of the disease, which are more severe, are caused by quantitative and qualitative anomalies of Type I collagen. The mutant Type I collagen molecules are secreted poorly and are susceptible to intracellular and extracellular degradation with loss of normal and mutant collagen chains. The mutant molecules severely impair the formation of the extracellular matrix causing an abnormal architecture of dermis and bone. The molecular pathology was correlated with the clinical, radiologic, and pathologic features. As a result, the clinical classification was expanded and a new biochemical classification of osteogenesis imperfecta was developed.