Craniodiaphyseal Dysplasia (CDD)

What is craniodiaphyseal dysplasia?

Craniodiaphyseal dysplasia (CDD), previously known as lionitis, is a rare condition that makes a child’s skull and facial bones develop incorrectly. CDD is a congenital condition. It’s present at birth. It makes your child’s body produce and store too much calcium in their skull.

In healthy amounts, calcium plays an important role in keeping your bones strong. But in children who have CDD, the extra calcium makes their skull bones grow too thick and large. The extra bone misshapes their face and puts extra pressure on the tissue and organs in their head. This can damage your child’s:

• Brain
• Eyes
• Inner ears
• Nasal passages
• Nerves

CDD can sometimes affect other bones in your child’s body, including their:

• Ribs
• Spinal bones

The extra bone growth can cause serious complications and damage. There’s no cure for craniodiaphyseal dysplasia. It gets worse over time and reduces a child’s lifespan significantly. Most children born with CDD live for around 20 years. Treatments can help your child manage symptoms and feel more comfortable.

Symptoms of craniodiaphyseal dysplasia

CDD symptoms will be most noticeable in your child’s facial features, including:

• A larger, fuller-than-usual lower jaw
• A noticeably long head
• A wide nose, especially between their eyes
• Bulging eyes
• Wider-set eyes

The thickened bones and increased pressure inside their skull can cause:

• Blurry vision
• Eye pain
• Headaches
• Seizures
• Sinus pressure or pain
• Trouble breathing
• Trouble hearing

Craniodiaphyseal dysplasia causes

CDD is a genetic disorder. A genetic change that affects the SOST gene causes it.

CDD is passed in an autosomal dominant pattern. If one birth parent has a changed SOST gene, their biological children will have a 50% chance of being born with CDD.

What are craniodiaphyseal dysplasia complications?

As your child’s skull bones get thicker and larger, they’ll put more pressure on the tissue under them. This can cause serious complications, including:

• Developmental disorders and learning disabilities
• Epilepsy
• Hearing loss (including deafness)
• Paralysis
• Vision loss

The increased pressure can also cause fatal brain damage.

How doctors diagnose this condition

A healthcare provider will diagnose CDD with a physical exam and some tests. They’ll examine your child and their facial bones. Tell your provider when you first noticed any symptoms or changes in your child.

Your provider will use X-rays to take pictures of your child’s skull and other bones. They might also use genetic testing to confirm your child has a changed SOST gene.

What are craniodiaphyseal dysplasia treatments?

Your provider will suggest treatments to manage any symptoms your child experiences.

Your child might need a cranioplasty. This is surgery to reshape their facial bones. But not every child with CDD can have this kind of surgery. It often has a high risk of complications. And there’s a good chance the bone tissue will regrow afterward.

Your provider may suggest treatments to manage specific symptoms or complications, including:

• Glasses or other visual aids to help with low vision
• Hearing aids to manage reduced hearing
• Occupational therapy to help your child complete everyday tasks
• Specialized dental treatments to help their mouth and teeth

Is there a cure for this condition?

There’s no cure for CDD. Many of the treatments are palliative. This means your provider will focus on making your child comfortable and improving their quality of life. They can’t stop or reverse CDD.

When should I see my healthcare provider?

Your provider will tell you how often your child will need follow-up visits. They’ll monitor your child’s bones and overall health for any changes. Your child may need regular X-rays to keep track of how their bones are growing.

Visit a healthcare provider if you notice any changes in your child’s facial features. Talk to a provider if they’re experiencing any new pain, or trouble hearing or seeing.

What is the prognosis for craniodiaphyseal dysplasia?

CDD is a progressive condition. It gets more severe over time. There’s no way to reverse or stop your child’s bones from growing incorrectly.

What is the life expectancy of someone with craniodiaphyseal dysplasia?

Children born with CDD often die in childhood. How long your child can expect to live depends on how quickly their skull bones grow. Any complications they experience can also affect their lifespan.

Is craniodiaphyseal dysplasia a disability?

Yes, CDD can be considered a disability. In the U.S., the Americans with Disabilities Act (ADA) guarantees legal and civil rights to people living with a disability. The U.S. Department of Justice Civil Rights Division has information online about accommodations.

Your provider can suggest resources or support groups for families managing CDD.