OSTEOGENESIS IMPERFECTA (OI)

Osteogenesis Imperfecta is a Hereditary Disease of the Connective Tissues characterized by sometimes having blue sclera and a strong tendency to bone fractures as a result of Osteoporosis which develops in 100% of the cases.  This diagnosis is more frequent among children than in adults.  It also has Autosomal Dominant Inheritance.

OI Classification   (Sillence Classification)

• Type I:  the most common form is autosomal dominant and is characterized by blue sclerae, a typical feature of OI. The number of fractures is fairly small and the deformities are modest, causing little loss of stature.

• Type II:  which is also autosomal dominant, is the lethal form of the disease. The sclerae are blue and death is due primarily to lung underdevelopment caused by rib fractures.

• Type III: is autosomal dominant or recessive and is the most severe non-lethal form. The sclerae are white, the face triangular, and the fractures commonly accompanied with progressive deformities and short stature.

• Type IV:  is autosomal dominant and usually characterized by white sclerae, short stature, and skeletal deformities that are less severe than those in type III. Type IV is the most heterogeneous group because it comprises those patients who do not meet the criteria for the other three types.

• Type V: characterized by hypertrophic calluses, sometimes mistaken for osteosarcomas, and by ossification of the interosseous membranes. Type V does not seem to be related to the COL1A1 or COL1A2 genes.