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Osteogenesis Imperfecta MedPix 2
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osteogenesis imperfecta is an inherited (autosomal dominant) disorder of collagen formation. Its incidence is about 1 in 30,000 with about 20,000 to 50,000 estimated cases in the United States. It is characterized by loss of bone density, bowing and fractures of bones. Abnormal maturation of the collagen molecule results in defective, weak bony matrix.
Four types are recognized and referred to as types I through IV. Type I is the most common and least severe type. In type I life expectancy is normal.. Fractures are common and tend to occur more in the lower extremities. Fractures are more common before puberty. Exuberant callous may occur with fracture healing. The fractures tend to cause bowing of the bones and mildly short stature. The underlying molecular defect in type I results in normal collagen molecules in decreased amount accounting for generalized osteopenia.
In type II OI collagen is improperly formed. Life expectancy is short â€“ often lethal at or shortly after birth.
Type III is rare. In type III collagen is improperly formed. fractures are very common and may occur at and before birth. All patients with type III have extreme short stature and almost all have scoliosis and vertebral compression.
Type IV is least common and is intermediate between type I and III in severity.
Non-osseous manifestations of OI include laxity of the joints, deafness and brittle teeth.
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Submitted by: admin
Added: Sun Dec 10 2006