What Is Brittle Bone Disease?
Brittle bone disease is a disorder that results in fragile bones
that break easily. It’s typically present at birth, but it only develops in children
who have a family history of the disease.
The disease is often referred to as osteogenesis imperfecta (OI),
which means “imperfectly formed bone.”
Brittle bone disease can range from mild to severe. Most cases
are mild, resulting in few bone fractures. However, the severe forms of the
disease can cause:
- hearing loss
- heart failure
- spinal cord problems
- permanent deformities
OI can sometimes be life-threatening if it occurs in babies
either before or shortly after birth. Approximately one person in 20,000 will develop
brittle bone disease. It occurs equally among males and females and among
What Causes Brittle Bone Disease?
Brittle bone disease is caused by a defect, or flaw, in the gene that
produces type 1 collagen, a protein used to create bone. The defective gene is
usually inherited. In some cases, however, a genetic mutation, or change, can
What Are the Types of Brittle Bone Disease?
Four different genes are responsible for collagen production. Some
or all of these genes can be affected in people with OI. Defective genes can produce
eight types of brittle bone disease, labeled as type 1 OI through type 8 OI.
The first four types are the most common. The last four are extremely rare, and
most are subtypes of type 4 OI. Here are the four main types of OI:
Type 1 OI
Type 1 OI is the mildest and most common form of brittle bone
disease. In this type of brittle bone disease, your body produces quality
collagen but not enough of it. This results in mildly fragile bones. Children
with type 1 OI typically have bone fractures due to mild traumas. Such bone
fractures are much less common in adults. The teeth may also be affected,
resulting in dental cracks and cavities.
Type 2 OI
Type 2 OI is the most severe form of brittle bone disease, and it
can be life-threatening. In type 2 OI, your body either doesn’t produce enough collagen
or produces collagen that’s poor quality. Type 2 OI can cause bone deformities.
If your child is born with type 2 OI, they may have a narrowed chest, broken or
misshapen ribs, or underdeveloped lungs. Babies with type 2 OI can die in the
womb or shortly after birth.
Type 3 OI
Type 3 OI is also a severe form of brittle bone disease. It causes
bones to break easily. In type 3 OI, your child’s body produces enough collagen
but it’s poor quality. Your child’s bones can even begin to break before birth.
Bone deformities are common and may get worse as your child gets older.
Type 4 OI
Type 4 OI is the most variable form of brittle bone disease
because its symptoms range from mild to severe. As with type 3 OI, your body
produces enough collagen but the quality is poor. Children with type 4 OI are
typically born with bowed legs, although the bowing tends to lessen with age.
What Are the Symptoms of Brittle Bone Disease?
The symptoms of brittle bone disease differ according to the type
of the disease. Everyone with brittle bone disease has fragile bones, but the severity
varies from person to person. Brittle bone disease has one or more of the
- bone deformities
- multiple broken bones
- loose joints
- weak teeth
- blue sclera, or a bluish color in the white of
- bowed legs and arms
- kyphosis, or an abnormal outward curve of the
- scoliosis, or an abnormal
lateral curve of the spine
- early hearing loss
- respiratory problems
- heart defects
How Is Brittle Bone Disease Diagnosed?
Your doctor can diagnose brittle bone disease by taking X-rays.
X-rays allow your doctor to see current and past broken bones. They also make
it easier to view defects in the bones. Lab tests may be used to analyze the
structure of your child’s collagen. In some cases, your doctor may want to do a
skin punch biopsy. During this biopsy, the doctor will use a sharp, hollow tube
to remove a small sample of your tissue.
Genetic testing can be done to trace the source of any defective
How Is Brittle Bone Disease Treated?
There’s no cure for brittle bone disease. However, there are
supportive therapies that help reduce your child’s risk of broken bones and
increase their quality of life. Treatments for brittle bone disease include:
- physical and occupational therapy to increase
your child’s mobility and muscle strength
- bisphosphonate medications to strengthen your
- medicine to reduce any pain
- low-impact exercise to help build bone
- surgery to place rods in your child’s bones
- reconstructive surgery to correct bone
- mental health counseling to help treat issues
with body image
What Is the Long-Term Outlook for Someone with Brittle Bone Disease?
The long-term outlook varies depending on the type of brittle
bone disease. Outlooks for the four main types of brittle bone disease are:
Type 1 OI
If your child has type 1 OI, they can live a normal life with
relatively few problems.
Type 2 OI
Type 2 OI is often fatal. A child with type 2 OI may die in the
womb or shortly after birth from respiratory problems.
Type 3 OI
If your child has type 3 OI, they may have severe bone
deformities and often require a wheelchair to get around. They usually have
shorter lifespans than people with type 1 or 4 OI.
Type 4 OI
If your child has type 4 OI, they may need crutches to walk. However,
their life expectancy is normal or close to normal.