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What Is Joubert Syndrome?

Medically Reviewed by Jabeen Begum, MD on October 13, 2022

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What Is Joubert Syndrome?

Joubert syndrome (JBTS) is a medical condition that primarily affects infants and children. In this condition, two parts of the brain known as the brain stem and the cerebellar vermis either underdevelop or fail to develop at all during pregnancy. The brain stem, which connects the brain to the spinal cord, helps to regulate vital body functions like breathing, heart rate, swallowing, blood pressure, and temperature control. Meanwhile, the cerebellar vermis helps to control coordination and balance as well as eye and head movements.

Joubert syndrome is known by various other names, including:

  • Joubert-Bolthauser syndrome
  • Cerebello-oculo-renal syndrome (CORS)
  • Agenesis of cerebellar vermis
  • Familial aplasia of the vermis

There are different clinical subtypes of Joubert syndrome with varying signs and symptoms. These subtypes are named differently depending on the part of the body they affect. Some of these are:

  • Joubert syndrome with retinal disease (JS-Ret)
  • Joubert syndrome with oculorenal disease (JS-OR)
  • Joubert syndrome w/hepatic disease (JS-H)
  • Joubert syndrome with renal disease (JS-Ren)
  • Joubert syndrome with oral-facial-digital features (JS-OFD)  
  • Joubert syndrome w/acro-callosal features (JS-AC)

How Common Is Joubert Syndrome? 

Joubert syndrome is rare. You may not be able to find more than a few hundred cases in the medical literature. Research shows that the chances of JBTS occurring every live birth fall between 1 in 80,000 and 1 in 100,000. But medical experts believe such estimates may be too low or misleading. Since people with Joubert syndrome show a wide range of signs and symptoms, some cases may either be misdiagnosed or not diagnosed at all. 

While it's not common to have this condition, some ethnic groups may have it more frequently than others due to the presence of certain genetic mutations in their communities. Such groups include the Hutterite, French-Canadian, and Ashkenazi Jewish populations. Moreover, JBTS runs in families. So, if you or your close relatives have this condition, there are greater chances that your child may also have it.

What Are the Causes of Joubert Syndrome? 

Experts have identified over 35 genes that cause Joubert syndrome to occur due to mutations in them. Over 60% to 90% of people with this condition have mutations in genes that are responsible for producing cell structures known as primary cilia. For this reason, JBTS is often grouped with other disorders known as ciliopathies. 

Primary cilia are tiny, fingerlike antennas that extend out from the surface of cells. These function like cellular sensors and help to gather information about the surrounding environment as well as communicate with other cells. Cilia help to maintain the function and structure of various kinds of cells, including those in the brain, liver, and kidney.  

Due to the genetic mutations seen in the case of JBTS, these cilia fail to develop properly. As a result, they don't function well, which affects the chemical signaling processes of the cells. This in turn causes certain structures in the brain and other parts of the body to develop abnormally.  

What Are the Symptoms of Joubert Syndrome? 

The symptoms of Joubert syndrome can vary widely, even in kids belonging to the same family. They can range from a few mild signs to severe problems in different parts of the body. 

To check for Joubert syndrome in your infant, you may want to look for:

  • Fast breathing
  • Weak muscle tone
  • Delays in intellectual development and picking up a language
  • Problems moving eyes sideways and other abnormal eye movements
  • Difficulty moving muscles voluntarily (ataxia) while walking, speaking, or picking up objects

In some cases of Joubert syndrome, you may also find the child having:

  • Tongue abnormalities
  • Distinct facial features (wide-spaced eyes, triangle-shaped mouth, lower-set ears, droopy eyelids)
  • Extra toes or fingers
  • Cleft palate and/or cleft lip

How Is Joubert Syndrome Diagnosed? 

A doctor may study your child’s physical symptoms and recommend an MRI to diagnose Joubert syndrome. Through the MRI images, your doctor would check the presence of “molar tooth sign” — a necessary criterion for diagnosing JBTS. When a part of the brain stem fails to develop properly, it looks like a molar tooth.

In addition, your doctor would also see if your child has:

  • Ataxia (problems with coordination, speech, and balance) with earlier problems in muscle tone (hypotonia) at the time of infancy
  • Intellectual problems or developmental delays.

An ob-gyn may detect problems with your child's brain development through a fetal ultrasound between 18 and 20 weeks of pregnancy. A geneticist may also test for the gene in your child's blood sample to find any specific genetic marker for Joubert syndrome. 

What Does the Treatment of Joubert Syndrome Include? 

The treatment of Joubert syndrome differs from one person to another. If your child has this condition, their treatment will depend on the kind of symptoms affecting them as well as the kind of support they need. 

Your child's developmental delays can usually be treated with:

  • Physical therapy
  • Speech therapy
  • Occupational therapy
  • Infant stimulation

If your child has problems breathing due to this condition, they may be given 

  • Mechanical support
  • Supplemental oxygen 
  • Tracheostomy (in rare cases)

If vision problems occur in your child due to JBTS, the doctor may recommend:

  • Corrective lenses (for refractive errors)
  • Special programs for educational support

For problems with the kidney or liver, your child may be given standard treatments. In severe cases, your child may need to undergo dialysis or liver/kidney transplantation. 

Since Joubert syndrome can affect different organs in your child, you may need to make regular visits to specialists like:

  • Neurologists (brain specialists)
  • Nephrologists (kidney specialists)
  • Ophthalmologists (eye specialists)

You may also want to talk to genetic counselors. They can confirm if any specific gene mutations run in your family and whether any other child of yours may also be at risk of having Joubert syndrome. 

The Takeaway 

While there's no way to prevent Joubert syndrome, genetic experts can help you to find out if your future children would be at risk. This can help you decide if you want to have your own kids. While some children with JBTS only have mild problems, others can have severe issues affecting their brain, kidney, liver as well as their eyes. In some cases, it can even be fatal for the child.

This is why you should immediately talk to a doctor if you notice any abnormal symptoms in your child. They can offer proper treatments to help improve the quality of your child's life and help you decide if anybody else in your family should get tested for Joubert syndrome.

Show Sources

SOURCES:
Cleveland Clinic: “Joubert Syndrome."
Great Ormond Street Hospital for Children: “Joubert’s syndrome."
MedlinePlus: “Joubert syndrome."
National Organization for Rare Disorders: “Joubert Syndrome."

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