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Symptoms & Early Signs of Joubert Syndrome

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The earliest signs of Joubert syndrome in infants typically include low muscle tone (hypotonia or 'floppiness'), irregular breathing patterns like panting or pauses, and abnormal eye movements. These symptoms are caused by a brain malformation diagnosed via the molar tooth sign on an MRI.

Key Takeaways

  • • Infants with Joubert syndrome often present with hypotonia, causing them to feel floppy and have difficulty supporting their head.
  • • Irregular breathing patterns, such as rapid panting or brief pauses, are common in the neonatal period but often improve over time.
  • • Abnormal eye movements, including nystagmus and oculomotor apraxia, frequently occur due to the underlying brain malformation.
  • • As infants grow, early low muscle tone often evolves into ataxia, a lack of muscle coordination that causes unsteadiness.
  • • Joubert syndrome is definitively distinguished from similar conditions by the presence of a molar tooth sign on a brain MRI.

The first months of a child’s life are filled with milestones, but for parents of a child with Joubert syndrome (JS), these early days often involve noticing subtle, yet distinct, physical and neurological signs. Because Joubert syndrome is a ciliopathy—a condition affecting the tiny “antennae” on cells—it impacts multiple systems, leading to a unique combination of symptoms that typically appear in infancy [1][2].

Core Early Symptoms

Most infants with Joubert syndrome will show a specific set of “classic” signs. These symptoms can vary greatly in intensity from one child to another, reflecting the “spectrum” nature of the disorder [1][3].

Low Muscle Tone (Hypotonia)

One of the most common early signs is hypotonia, or decreased muscle tone [4][5]. In plain language, a baby with hypotonia may feel “floppy” when held. They may have difficulty supporting their head, and their limbs may hang more loosely than expected for their age [2][6].

Irregular Breathing Patterns

In the neonatal period (the first 28 days of life), many infants with JS exhibit unusual breathing [4][2]. This often includes:

  • Hyperpnea: Periods of very fast, deep breathing, similar to panting [5][7].
  • Apnea: Brief pauses in breathing, which can sometimes alternate with hyperpnea [5][2].
    While these episodes can be alarming, they often improve or become less frequent as the child grows, though some sleep-related breathing issues may persist [8][9].

Abnormal Eye Movements

The brain malformation in JS often affects the nerves that control how the eyes move [10][11]. Parents and doctors may notice:

  • Nystagmus: Involuntary, rhythmic “jiggling” or “dancing” of the eyes [12][13].
  • Oculomotor Apraxia (OMA): A difficulty in starting voluntary eye movements. To look at something to the side, a child might move their head first and then wait for their eyes to “catch up” [12][13].
  • Strabismus: Eyes that do not line up in the same direction (commonly called “crossed eyes”) [12].

Developmental Delay and Ataxia

As infants grow, they may experience global developmental delay, meaning they take longer to reach milestones like sitting, crawling, or babbling [14][5]. Later in childhood, the early hypotonia often evolves into ataxia, which is a lack of muscle coordination that can cause shakiness or an unsteady gait [14][5].

Conditions Often Confused with JS

Because some of these signs—like “floppiness” or breathing pauses—can happen in many different conditions, JS is sometimes initially misdiagnosed [15]. Common conditions that can look like JS in the beginning include:

  • Dandy-Walker Malformation (DWM): Another brain malformation that also involves the cerebellum (the part of the brain responsible for balance) [16][17]. Note: Prenatal ultrasounds can sometimes misidentify JS as Dandy-Walker malformation, which is why a postnatal MRI is necessary to confirm the exact diagnosis.
  • Poretti-Boltshauser Syndrome (PBS): A disorder that causes similar coordination issues but lacks the characteristic “molar tooth sign” on an MRI [18].
  • Meckel-Gruber Syndrome (MKS): A more severe ciliopathy that can share features like kidney cysts or extra fingers (polydactyly) [19][3].

The definitive way to distinguish Joubert syndrome from these other conditions is the presence of the molar tooth sign on a brain MRI and confirmed genetic testing [11][15].

Variability and Progression

It is important to remember that every child’s experience with Joubert syndrome is different. Some children may have very mild symptoms, while others may face more significant challenges [1][20]. While core issues like coordination and delays persist, many children make steady progress through physical and occupational therapy, learning to adapt and gain new skills as they grow [14][7].

Frequently Asked Questions

What are the first signs of Joubert syndrome in a baby?
Early signs usually include low muscle tone making the baby feel floppy, unusual breathing patterns like rapid panting or pauses, and abnormal eye movements. These signs typically appear in the first few months of life.
How is Joubert syndrome different from Dandy-Walker malformation?
While both are brain malformations affecting the cerebellum, Joubert syndrome is uniquely identified by the 'molar tooth sign' on a postnatal brain MRI. Prenatal ultrasounds can sometimes confuse the two conditions, making an MRI essential for a definitive diagnosis.
Will the unusual breathing patterns in my baby improve?
Yes, the fast breathing (hyperpnea) and pauses in breathing (apnea) seen in newborns often improve or become less frequent as the child grows. However, some sleep-related breathing issues may persist.
What does oculomotor apraxia look like?
Oculomotor apraxia is a difficulty in starting voluntary eye movements. A child with this symptom might move their head first to look at something to the side, and then wait for their eyes to catch up.
Can children with Joubert syndrome make developmental progress?
Yes, while every child's experience is different, many children make steady developmental progress. With the help of physical and occupational therapy, they can learn to adapt and gain new skills as they grow.

Questions for Your Doctor

  • • Based on our child's symptoms, how do you differentiate Joubert syndrome from other similar conditions like Dandy-Walker malformation?
  • • What specific types of abnormal eye movements are you seeing in our child (e.g., oculomotor apraxia or nystagmus)?
  • • Should we be concerned about our child's breathing patterns, and do they require a formal sleep study?
  • • How often should we re-evaluate our child's developmental milestones to monitor their progress?
  • • Are there specific 'red flags' related to hypotonia or breathing that we should watch for at home?

Questions for You

  • • What was the first sign we noticed that seemed different about our baby's movement or development?
  • • Have we noticed any patterns in our child's breathing, such as very fast breathing or short pauses, especially when they are sleeping or active?
  • • Does our child seem to have trouble following objects with their eyes, or do they move their head in a specific way to look at something?
  • • How would we describe our child's muscle tone—do they feel particularly 'floppy' when we pick them up?

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References

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    Mutations in KIAA0753 cause Joubert syndrome associated with growth hormone deficiency.

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This page explains the early signs and symptoms of Joubert syndrome for educational purposes only. Always consult your pediatrician or a pediatric neurologist for a proper medical evaluation of your child's symptoms.

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