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Alternative namesBrittle bone disease
DefinitionOsteogenesis imperfecta is a congenital (present from birth) condition of abnormal fragility of the bones.
Causes, incidence, and risk factors
This bone disorder is usually present at birth as an inherited disease. Osteogenesis imperfecta (OI) is classified into four major types (and further subtypes).
All four types of OI are caused by defects in the amount or structure of Type 1 collagen, an important part of the bone matrix. The collagen problem usually results from a dominant genetic defect. This defect may be acquired by several different mechanisms:
When people have OI, all of their bones are abnormally weak. The severity of the abnormality varies enormously -- from Type II OI, which is usually lethal in infancy (or even before birth) to Type I OI, which may be so mild that the diagnosis is not made, even in adulthood.
The three classic symptoms of OI includes fragile bones, early hearing loss, and whites of the eyes that appear bluish (blue sclerae). Nevertheless, not all people with OI will have blue sclerae or hearing loss. All do have fragile bones, but not all people with OI actually ever break a bone.
A variety of other symptoms may be found in the various types of OI:
Signs and tests
A physical examination may confirm the presence of fractures , deformities, and other symptoms.
Bone X-rays may show multiple healed fractures.
The diagnosis is made by collagen studies done on a skin punch biopsy. Once the specific molecular diagnosis is known, family members can be tested by a DNA blood test. DNA testing on prenatal chorionic villus samples (CVS) can make the diagnosis during pregnancy.
Severe OI is visible on prenatal ultrasound as early as 16 weeks.
Fractures must be repaired quickly in the usual ways to avoid deformities. There is no specific treatment for the underlying disease. However, there are several therapies that can improve the quality of life for patients with OI.
Permanent deformity of the extremities may occur. Brain damage may result from skull fractures . The disorder can be fatal. The disease is grouped by type:
Calling your health care provider
This disorder is often diagnosed at birth, but mild cases may not be detected until later in life. Call for an appointment with your health care provider if symptoms suggestive of this disorder occur.
Genetic counseling is recommended for prospective parents if one or both are affected by this disorder.
Update Date: 7/26/2002Elizabeth Hait, M.D., Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT