Inherited Brittle Bones (Osteogenesis Imperfecta)

What is osteogenesis imperfecta?

Osteogenesis imperfecta (OI) is an inherited disease that causes very weak bones.

There are 8 main types of OI.

• People with type 1 tend to have mild symptoms.
• People with types 2, 3, 7, and 8 tend to have severe symptoms.
• People with types 4, 5, and 6 tend to have more moderate symptoms.

Type 1 OI may not be diagnosed until late childhood or the teenage years. Other types may be diagnosed when a baby is born. In the severest cases the baby’s bones may break before birth and the baby may be born dead. In other severe or moderately severe cases, you may become wheelchair bound or need braces or crutches to walk.

OI can cause deformed bones. Broken bones will heal, but in the process of healing they may get deformed.

What is the cause?

OI is caused by a problem with the genes that make collagen. Collagen is needed for strong bones and other tissues. If your collagen is not normal or there is not enough of it, bones will be weak and break easily.

Usually the gene for the disease is inherited from the parents.

What are the symptoms?

The symptoms of this disease vary greatly, even among people with the same type of the disease. Symptoms may include:

• bones that break very easily, often from little or no cause (the most common symptom)
• whites of the eyes that are blue or have a purple or gray shade
• early hearing loss
• shorter height than normal
• teeth that are dark colored or break easily
• curving of the spine (scoliosis)
• weak muscles and less ability to exercise
• easy bruising
• problems with breathing
• constipation
• loose joints
• thin, smooth skin
• high-pitched voice

Most fractures start happening in infancy or early childhood. Fractures happen less often as a child goes through puberty. Women with OI have more fractured bones after menopause. Men may start to break more bones after age 60.

How is it diagnosed?

Sometimes a mild case of OI may not be noticed until a bone breaks. Your healthcare provider will ask about your medical and family history and examine you. Tests may include:

• blood tests to check the genes
• skin biopsy to test the collagen (a biopsy is removal of a small piece of skin for lab tests)

Although these are the best tests for OI, sometimes the test result may be negative even though you have OI.

How is it treated?

Your healthcare provider will refer you to a specialist for treatment, such as an orthopedist (a doctor who specializes in bones) or an endocrinologist (a doctor who specializes in disorders of hormones). The OI Foundation can provide referrals to OI experts. You may also need to see other specialists, such as a physical therapist or an ear, nose, and throat specialist.

Goals of treatment are to manage the symptoms, prevent problems and injuries, and keep the bones and muscles as strong as possible. Treatment includes:

• Medicine: Medicine is used to help reduce pain, strengthen bone, and reduce the number of broken bones. The medicine may be given every few months by vein (IV).
• Exercise: Exercise should become part of your daily routine. If you have a milder form of OI, walking and swimming are good ways to keep your muscles strong.

Sometimes surgery may be done. For example, rods may be put into long bones in arms or legs to support the bones.

How can I take care of myself?

• Get regular exercise but try to avoid activities that may cause fractures. Don’t play contact sports.
• Eat a healthy diet and keep a healthy weight.
• Don’t smoke.
• Ask your healthcare provider:
  • how and when you will hear your test results
  • if there are medicines you should avoid
  • what activities you should avoid and when you can return to your normal activities
  • how to take care of yourself at home
  • what symptoms or problems you should watch for and what to do if you have them
• Make sure you know when you should come back for a checkup.

How can this disease be prevented?

If you have OI, or there is OI in your family medical history, it is a good idea to talk with a genetic counselor before you start a family.

For more information, contact the OI Foundation at 800-981-2663 or visit the Web site at http://www.oif.org.