| Additional Info: |
In a bone marrow biopsy done for other reasons, we found prroly and focally mineralized bone with areas of remodeling (abundant osteoblastic and osteoclastic activity). Searching the records a little more, we discovered this patient has a history of osteogenesis imperfecta!
Osteogenesis imperfecta, or "brittle bone disease" occurs as a result in qualitative or quantitiative defects in Type I collagen. Almost 90% of cases are due to mutations in genes COL1A1 and COL1A2, which encide for the alpha-1 and and alpha-2 subunits of collagen. 35% of mutations arise de novo, while those that are inherited are most frequently autosomal dominant.
Phenotypically there is a wide range of variability in presentation. Classic findings include numerous bone fractures, blue discoloration of the sclera, and hearing loss.
Type I OI (the most common), is a mild form, while Type II is extremely severe and almost universally fatal in the perinatal period. Types III and IV are mild to moderate in phenotype. Types V through VIII are secondary to gene mutations other than COL1A1/2, including CRTAP and LEPRE1. |