Joubert syndrome is a rare genetic condition that causes underdevelopment in a part of the brain called the cerebellar vermis and malformation of the brainstem.

The cerebellar vermis coordinates movements of your head, trunk, and upper limbs. The brain stem controls functions like breathing, blood pressure, and heart rate. Joubert syndrome affects both.

Joubert syndrome goes by several other names:

  • Joubert-Bolthauser syndrome
  • cerebellooculorenal syndrome 1
  • cerebelloparenchchymal disorder IV familial

We examine Joubert syndrome in more depth, including its symptoms, causes, and outlook.

The National Organization for Rare Disorders estimates that Joubert syndrome develops in 1 in 80,000 to 1 in 100,000 live births.

Researchers have found it to occur in about 1 in 34,000 to 1 in 40,000 people of Ashkenazi Jewish background due to a mutation in the TMEM216 gene. Canadian Hutterites have about a 1 in 1,150 chance of developing Joubert syndrome due to a mutation in the TMEM237 gene.

Most signs and symptoms of Joubert syndrome appear in infancy. They can range from mild to severe.

Signs and symptoms include:

What are the behaviors of a person with Joubert syndrome?

People with Joubert syndrome may develop a variety of behavioral issues related to:

In 2018 case studies, researchers performed comprehensive neurological and psychological evaluations on three brothers with Joubert syndrome. They found:

  • The first brother had auditory and visual hallucinations that resulted in multiple hospitalizations.
  • The second brother had depression and general anxiety disorder.
  • The third brother was hospitalized twice in his 20s for:

All three brothers had:

  • a history of behavioral and emotional dysregulation
  • intellectual disability
  • coloboma, a hole in one of the structures of the eye

Subtypes of Joubert syndrome

Joubert syndrome can be divided into subtypes depending on the major features. Subtypes include:

Classic Joubert syndrome• problems with eye movement
• breathing problems
• extra fingers or toes
Joubert syndrome with retinal disease• retina problems
Joubert syndrome with renal disease• kidney problems
Joubert syndrome with oculorenal disease• retina and kidney problems
Joubert syndrome with hepatic disease• liver problems
Joubert syndrome with oral-facial-digital features• cleft lip and palate
• tongue problems
• extra fingers or toes
Joubert syndrome with acrocallosal features• atypical development of the tissue that connects the left and right sides of the brain
Joubert syndrome with Juene asphyxiating dystrophy• extra fingers or toes
• narrow rib cage
• short stature

Joubert syndrome can develop due to gene mutations inherited from birth parents or from gene mutations that develop sporadically.

Mutations in more than 40 genes linked to Joubert syndrome have been discovered. These gene mutations explain 94% of Joubert syndrome cases. The genetic cause of the remaining 6% of cases still isn’t known.

Some of the most common causes include mutations in:

  • AHI1
  • CEP290
  • NPHP1

Joubert syndrome is particularly common in certain groups, including:

  • French Canadians
  • Ashkenazi Jews
  • Hutterites

Males develop Joubert syndrome about twice as often as females.

Joubert syndrome inheritance

Most of the genes associated with Joubert syndrome are recessive, meaning you need to inherit one associated gene from each parent to develop Joubert syndrome.

One rare mutation on the OFD1 gene associated with Joubert syndrome is found on the X chromosome. Females have two X chromosomes and males have one.

Females carrying this OFD1 gene mutation have a 25% chance of having:

  • a daughter who carries the gene
  • a daughter who doesn’t carry the gene
  • a son who has Joubert syndrome
  • a son who doesn’t have Joubert syndrome

Males with this gene have a 100% chance of passing Joubert syndrome to their daughters and a 0% chance of passing it to their sons.

Joubert syndrome is a genetic condition. There’s currently no known way to prevent it.

The following three criteria need to be met to diagnose Joubert syndrome:

  1. A molar tooth sign on an MRI. This is when doctors can see your cerebellar vermis is absent and your brainstem is atypical. On an MRI, a healthcare professional will see a pattern resembling a tooth.
  2. Weak muscle tone (hypotonia) occurs in infancy, with later issues with coordination (ataxia).
  3. Developmental delays or intellectual delays are present.

A blood test can also show if you have genes associated with Joubert syndrome.

Joubert syndrome doesn’t currently have a cure. Treatments revolve around managing the health problems that may develop.

Potential treatment options include:

The life expectancy for people with Joubert syndrome depends on the severity of the disease. Some people live into adulthood.

In a 2017 study, researchers found that the average age of death among 40 people with Joubert syndrome was 7.2 years. The most common causes of death were respiratory failure and kidney failure.

This is a serious, life altering condition.

Finding out that your child has Joubert syndrome can be difficult. You may worry about how it will affect their health and quality of life.

You’re not alone in this. The Joubert Syndrome & Related Disorders Foundation is a volunteer-run nonprofit that provides resources and support for parents of children with Joubert syndrome.

Enrolling your child in clinical trials can help researchers improve their understanding of the disease. You can find a list of current clinical trials from the National Library of Medicine website.

Joubert syndrome can lead to many different problems, such as retinal issues, physical changes and differences, and intellectual disability.

The outlook for children with Joubert syndrome varies depending on the severity of their disease. Children with mild disease may live into adulthood.