Osteopetrosis

What Is Osteopetrosis?

Osteopetrosis is a rare condition that causes bones to become unusually dense and hard. Although the bones may look strong, they’re actually more fragile and can break easily. In some cases, the extra bone growth can put pressure on nearby organs and nerves. When bone becomes too dense, it can also crowd out the bone marrow — the part of the bone that makes blood cells needed to carry oxygen, fight infection, and help with clotting.

What Causes Osteopetrosis?

Osteopetrosis is a genetic condition, meaning it’s caused by changes (variants) in certain genes that can be passed down in families. These gene changes prevent the body from making enough of a specific kind of bone cell called an osteoclast, which normally breaks down old bone. Without enough working osteoclasts, the body can’t rebuild bone properly — leading to bones that are dense but brittle.

There are several types of osteopetrosis, and they differ in severity:

• Autosomal recessive osteopetrosis (ARO): The most severe form, usually diagnosed in infancy. It occurs when a child inherits two copies of the affected gene (one from each parent).
• Autosomal dominant and X-linked osteopetrosis: These forms are typically milder and happen when only one copy of the affected gene is inherited.

What Are the Signs & Symptoms of Osteopetrosis? 

Children with osteopetrosis can have a range of symptoms, which may include:

• Frequent or unexplained bone fractures
• Low blood cell counts, leading to fatigue or frequent infections
• Chronic bone pain
• Vision or hearing changes, sometimes progressing to blindness or deafness
• Nasal congestion or breathing difficulties
• Dental problems, such as delayed tooth eruption or fragile teeth

How Is Osteopetrosis Diagnosed?

To confirm a diagnosis, your child’s doctor may recommend:

• Genetic testing to look for variants in the genes that cause osteopetrosis
• Blood tests to check blood cell counts and organ function
• Imaging tests, such as X-rays, bone density scans (DXA), MRI of the brain, or a kidney ultrasound to look for bone and organ changes

How Is Osteopetrosis Treated?

Treatment depends on the type and severity of the condition. Your child’s care team will tailor recommendations to their specific needs. Common treatments may include:

• Calcium and vitamin D supplements to support bone health
• Steroids to help improve blood cell levels
• Interferon-gamma 1b therapy to slow disease progression in severe cases
• Bone marrow transplant, which may be recommended for the most serious form (autosomal recessive osteopetrosis) and can be lifesaving

What Are the Long-Term Effects of Osteopetrosis?

Outcomes vary depending on the type of osteopetrosis.

• In the severe infant form, a bone marrow transplant may be needed to prevent life-threatening complications.
• In the milder forms, children and adults can live full lives with ongoing monitoring and treatment to manage symptoms.