Definition

Osteogenesis imperfecta (OI) is a genetic problem that affects the bones. The most common effect is weakened bones that break easily. There are at least 8 types of OI. Some are mild with no obvious signs, while others are more severe.

The Bones of the Body Copyright © Nucleus Medical Media, Inc.

Causes

OI is caused by a problem in:

• The gene that controls the making of collagen—an important element in bones and connective tissues:
  • Most common cause of OI
  • Most often caused by a random change in the gene; not often associated with a family history
• The gene that controls proteins in cartilage:
  • Less common cause of OI
  • An inherited genetic change from parents; there is often a family history

Risk Factors

A family history of OI may increase your risk of certain types of the disease. There are no known risk factors for most types of OI.

Symptoms

In the 4 most common types of OI, symptoms may include:

• Bone pain
• Hearing loss
• Whites of the eyes may have a blue, purple, or gray tint
• Bone deformity
• Short height
• Loose joints and muscle weakness
• Triangular face
• Brittle teeth
• Breathing problems
• Bruising easily

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. OI may be diagnosed based on your history of fractures or appearance alone.

Your bones may need to be examined. This can be done with:

• X-rays
• Bone mineral density test
• Bone biopsy

Genetic testing may be done. This can help determine the type of OI. Genetic testing can be done through a blood, saliva, or skin biopsy.

If you are pregnant and have a family history of OI your doctor may do:

• Ultrasound —to look for skeletal problems before birth, which will only show in certain types of OI
• Chorionic villus sampling (CVS)—for genetic testing

Treatment

There is presently no cure for OI. In general, treatment is directed toward:

• Preventing health problems
• Improving independence and mobility
• Developing bone and muscle strength

Some supportive treatment options include:

• Medication called bisphosphonates—to increase bone mineral density
• Physical therapy—for range of motion and muscular strength exercises
• Surgical implant of rods into long bones—to provide strength and prevent or correct deformities
• Monitoring for fractures or scoliosis
• Assistive devices like braces, canes, or wheelchairs—may be needed with certain types of OI
• Dental procedures

Problems related to OI, such as fractures, can be reduced or prevented by a healthy lifestyle. This should include:

• Exercise—swimming is often an ideal and safe activity
• Good nutrition
• Not smoking
• Avoiding excessive amounts of alcohol

Prevention

OI is caused by a genetic defect. There is no known way to prevent it.

Genetic counseling may be useful if you are planning to have a child and you have OI or a family history of OI. The counselor can let you know the risk your child may have of developing OI.