Joubert Syndrome

What is Joubert syndrome?

Joubert syndrome is a rare genetic disorder that happens when the part of a fetus’s brain doesn’t develop as it should. The syndrome has many subtypes that cause different symptoms, but it typically causes issues with muscle control or muscle tone, breathing and eye movement.

Each year, 1 in 100,000 babies worldwide are born with Joubert syndrome. Most children with Joubert syndrome inherit genetic mutations that cause it, but it can also happen sporadically (for no known reason)

What are the symptoms of Joubert syndrome?

Joubert syndrome causes different conditions and may change as children grow up. Symptoms may include physical differences, including facial differences, symptoms of certain eye conditions, and liver and kidney disease.

Your child may have the following neurological issues or conditions:

• Hypotonia (decreased muscle tone) that becomes ataxia (issues with muscle coordination).
• Eye conditions like nystagmus or strabismus (crossed eyes).
• Breathing issues like tachypnea (fast, shallow breathing) or apnea (breathing that pauses).
• Developmental delay.
• Intellectual disability.

Physical differences

Your child may have the following issues or symptoms:

• Cleft lip and palate.
• Distinctive facial features like a broad forehead, droopy eyelids (ptosis) or eyes that are spaced wider than usual. Their ears may be set lower than usual, and their upper lip may turn up in the center so their mouths are shaped like a triangle.
• Polydactyly (extra fingers and toes).
• Protruding tongue.

Medical conditions

As they grow up, your child may develop medical conditions that affect their retinas (the part of your eye that converts light to images), kidneys and liver. For example, children may develop conditions like Leber’s congenital amaurosis, polycystic kidney disease or liver failure.

What causes Joubert syndrome?

Joubert syndrome can be the result of mutations in more than 35 different genes that play a part in brain development. Most of the time, people inherit these mutations in an autosomal recessive manner, which means both biological parents pass on the genetic mutations that cause Joubert syndrome.

But one of these mutations is X-linked, meaning the change is on the X chromosome. Mutations on the X chromosome can pass in a dominant or recessive pattern, but not every pattern is clear on how a child acquires the mutation from their parents.

The genetic mutations that cause Joubert syndrome result in abnormal versions of your child’s cerebellum, brainstem and cilia:

• The cerebellum manages coordination and movement. In Joubert syndrome, the cerebellar vermis is missing or is smaller than normal.
• The brainstem, which regulates breathing and balance, doesn’t form correctly. When viewed on imaging scans, the abnormal cerebellar vermis and brainstem look like a molar tooth. Spotting that image, which healthcare providers may call molar tooth sign, is one way that they diagnose Joubert syndrome.
• Cilia are tiny structures that stick out from cells’ surfaces, like antennas from the top of a building. Cilia on brain cells help them communicate with each other during organ development. Researchers believe mutations that affect cilia may cause eye, kidney and liver issues in people with Joubert syndrome.

How do these genetic mutations affect family members?

That depends on factors like the type of genetic mutation and sex:

• Autosomal recessive inheritance: Children with a biological sibling who has Joubert syndrome have a 25% chance of developing the condition, a 50% chance that they’ll carry the genetic mutation but not have symptoms, and a 25% chance that they won’t carry the mutation or have symptoms.
• X-linked inheritance: Children assigned male at birth have a 50% chance of developing the condition. But if they don’t develop symptoms, they aren’t carriers. Children assigned female at birth have a 25% chance of developing the condition and a 50% chance that they won’t have symptoms but will carry the genetic mutation.

How is Joubert syndrome diagnosed?

Healthcare providers consider your child’s symptoms and imaging test results to diagnose Joubert syndrome. The criteria for diagnosing the condition are:

• Molar tooth sign that’s visible on a brain MRI.
• Hypotonia symptoms.
• Development delay.

Providers may order genetic tests to confirm your child’s diagnosis and treatment. Studies show between 62% and 94% of children with Joubert syndrome have one of the genetic mutations that cause it. Identifying the specific mutation helps providers anticipate the kinds of health issues your child may have so they can treat them early on.

Do prenatal tests diagnose Joubert syndrome?

They can, but not always. Differences in a fetus’ brain stem or cerebellum may show up in a prenatal MRI. But a fetus may have brain abnormalities that don’t show up on an MRI scan.

What are the treatments for Joubert syndrome?

Treatments are different for each child and depend on factors like the syndrome type and how it affects them. For example:

• If your baby has breathing difficulties, they may receive breathing support like supplemental oxygen or mechanical ventilation.
• Children of all ages with developmental delays may receive physical therapy, speech and language therapy and occupational therapy.
• A child with strabismus (an eye condition) may have strabismus surgery.

Depending on the ways Joubert syndrome affects your child, you might need regular visits with specialists who’ll diagnose, monitor and treat issues like kidney disease, eye issues and neurological issues.

Can I prevent Joubert syndrome?

There isn’t a way to prevent Joubert syndrome. But geneticists and genetic counselors can help determine who in your family may be at risk. That information can help people decide whether to have children, for example.

What can I expect if my child has Joubert syndrome?

The outlook for babies and children with Joubert syndrome depends on factors like how a specific genetic mutation affects your child. In general, children with Joubert syndrome will need medical treatment and other support for the rest of their lives. Your child’s healthcare provider is your best resource for information about what you can expect.

What is the life expectancy for a baby born with Joubert syndrome?

Joubert syndrome can be fatal in childhood, but people with the condition can live into adulthood. Researchers are still studying life expectancy with this rare condition. And your child’s situation is unique to them, including how the condition affects them. It’s natural to want to know how long your child will live, and your child’s healthcare team is your best source of information on what to expect.

When should my child see their healthcare provider?

Joubert syndrome symptoms can change during your child’s life. Your child will need annual checkups so their healthcare provider can evaluate:

• Their growth and development.
• Their vision.
• Their liver and kidney function.

Your child may need periodic neurological examinations and development tests. They also may need specialized care to treat eye issues, kidney disease or liver disease.

How do I take care of myself and my family?

Joubert syndrome changes family life, potentially putting pressure on everyone who loves and cares for a child with the condition. If you have a child with Joubert syndrome, some of these ideas may help:

• Support groups: Joubert syndrome is rare. You may feel your family is the only one facing the challenges. Joining a support group connects you with other parents, caregivers and families living with the same challenges.
• Counseling: Working with a psychologist or other mental health professional may help you and other family members manage stress, anxiety and other feelings.
• Get involved: Joubert syndrome happens for reasons you can’t control. That can make you feel helpless. If that’s your situation, consider getting involved with organizations that support programs and research.

What questions should I ask my child’s doctor?

You’ll probably have many questions about your child’s needs now and in the future. Here are some suggestions:

• What disabilities can we expect to see?
• What specialists do we need to see?
• How often should we see them?
• Will my child need surgery?
• What is our child’s life expectancy?
• Should other family members get genetic testing?