What Is Osteogenesis Imperfecta?
Osteogenesis imperfecta (OI), also known as brittle bone disease, is a genetic condition characterized by bones that break easily, often for little or no apparent reason. The condition can literally be translated as "imperfectly formed bones."
Collagen is the major protein of the body's connective tissue and is the framework upon which bone and tissue are built. It can be compared to the framework around which a building is constructed. If the collagen framework is defective, the bones fracture easily, the skin is loose and transparent, and the muscles lack tone. People with osteogenesis imperfecta either have less collagen than normal or a poorer quality of collagen.
How Common Is Osteogenesis Imperfecta?
While the number of people affected with osteogenesis imperfecta in the United States is unknown, the best estimate suggests a minimum of 20,000 and possibly as many as 50,000. This condition also affects people in other countries throughout the world.
The
cause of osteogenesis imperfecta, in most cases, is a dominant genetic defect (known as autosomal dominant) in the genes responsible for making collagen. Some children with the condition inherit the disorder from a parent. Other children are born with osteogenesis imperfecta, even though there is no family history of the disorder. In these children, the genetic defect occurred as a spontaneous mutation.
Types of Osteogenesis Imperfecta
In 1979, Sillence and others devised a classification scheme that divides osteogenesis imperfecta into four types (two additional types have subsequently been added).
- Type I OI
- Type II OI
- Type III OI
- Type IV OI
- Type V OI
- Type VI OI.
Symptoms of Osteogenesis Imperfecta
Osteogenesis imperfecta symptoms vary significantly according to type, and it is difficult to predict what symptoms or complications a person will have.
The characteristic symptoms of the condition also vary greatly from person to person, even among people with the same type of osteogenesis imperfecta, and even within the same family. In addition, not all symptoms are evident in each case.
Common symptoms include:
- Bones that fracture easily
- Short stature
- Skeletal deformities of limbs, chest, and skull
- Scoliosis (curvature of the spine)
- Hearing loss
- Respiratory difficulties
- Loose joints and ligaments
- Discolored, brittle teeth
- Blue sclera (blue color in the whites of the eyes)
- Constipation
- Weak muscles
- Excessive sweating
- Tendency to bruise easily
- High-pitched voice.
Keep in mind that very few people with the condition exhibit all of these symptoms and that the severity of each symptom can vary tremendously between individuals.
In order to make an
osteogenesis imperfecta diagnosis, the doctor will ask a number of questions about a person's medical history (for example, current symptoms and family history of any medical problems). The doctor will also perform a physical exam to look for any signs of the disorder; the doctor may also order certain tests.
Tests used to make a diagnosis can include a collagen biopsy or DNA test.
Bone densitometry (also known as a
bone density test or
bone density scan) will not, by itself, provide a diagnosis. However, when combined with personal and family medical history, findings on physical examination, x-rays, and biochemical testing, a bone densitometry can provide important information to support an osteogenesis imperfecta diagnosis.
Treatment Options for Osteogenesis Imperfecta
There is no cure for osteogenesis imperfecta yet. Therefore, treatment is typically directed toward:
- Preventing or controlling symptoms
- Maximizing independent mobility
- Developing optimal bone mass and muscle strength.
Care of fractures, extensive surgical and dental procedures, and physical therapy are often recommended for people with the condition. Use of wheelchairs, braces, and other mobility aids is common, particularly (although not exclusively) among people with more severe
types of osteogenesis imperfecta.
To date, no drug or vitamin therapy regimen has been effective as an
osteogenesis imperfecta treatment. Researchers who study the disorder continue to make progress with these issues.
Children With Osteogenesis Imperfecta
In most ways, caring for a child with this condition is just like caring for any other child. There are, however, a few precautions and tips unique to handling
children with osteogenesis imperfecta.
Some special areas of consideration in caring for babies and children with the disorder include:
Other Information on Osteogenesis Imperfecta
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