Osteogenesis imperfecta type III is a severe type of osteogenesis imperfecta (OI; see this term), a genetic disorder characterized by increased bone fragility, low bone mass and susceptibility to bone fractures. The main signs of type III include very short stature, a triangular face, severe scoliosis, grayish sclera, and dentinogenesis imperfecta (DI; see this term).
The overall prevalence of OI is estimated at between 1/10,000 and 1/20,000 but the prevalence of type III is unknown.
OI type III can be autosomal dominant and caused by mutations of the COL1A1 and COL1A2 genes (17q21.31-q22 and 7q22.1 respectively), or it can be autosomal recessive and caused by mutations of the CRTAP gene (3p22) (sometimes described as OI type VII) or the LEPRE1 gene (1p34) (sometimes described as OI type VIII) or the PPIB gene (15q21-q22) (sometimes described as OI type IX).
- Dr Véronique FORIN