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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Neurology · Joubert syndrome

What Is a Ciliopathy & How Does It Cause Joubert Syndrome?

At a Glance

Joubert syndrome is a ciliopathy caused by defects in primary cilia, which act as tiny cellular antennae that help cells communicate. Because these cilia are found on almost every cell, a single defect can impact the development of multiple organs, including the brain, kidneys, eyes, and liver.

When doctors say your child has a “ciliopathy,” they mean that your child’s condition is caused by a problem with tiny structures on their cells called primary cilia [1]. Because these structures exist on almost every cell in the human body, a single genetic difference can affect how multiple organs—like the brain, kidneys, liver, and eyes—develop and work [2][3]. Joubert syndrome is one type of ciliopathy [4]. It is important to know that every child is unique; the combination and severity of the organs affected vary widely, and your child may not develop all of these issues [5][6].

The “Cellular Antennae” Analogy

To understand a ciliopathy, it helps to know what a primary cilium does. You can think of primary cilia as microscopic “cellular antennae” that stick out from the surface of a cell [7][2].

Just like a radio antenna picks up signals from the air to play music, a primary cilium picks up signals from the body’s environment [2][8]. These signals tell the cell what is going on around it, such as changes in light, physical pressure, or chemical messages from other parts of the body [7].

During pregnancy, these antennae are incredibly important [3]. As a baby grows, cells rely on their antennae to receive the instructions needed to build complex organs [9][10]. If the antennae are missing, poorly shaped, or unable to send messages properly, the cells don’t get the right instructions, and the organs may not form exactly as they should [4].

Why It Affects So Many Organs

It can be overwhelming to hear that your child’s brain, eyes, liver, and kidneys might all need monitoring. It might seem like several different conditions are happening all at once. However, because nearly all cells use primary cilia, a single defect in these antennae can impact any organ that relies on them [2][9].

Here is how broken antennae can impact specific areas in Joubert syndrome:

  • The Brain: During development, brain cells use their cilia to read a specific chemical signal that tells the brain how to grow [4][11]. When the antennae don’t work, a specific part of the brain called the cerebellum does not fully develop [4]. On an MRI scan, this underdeveloped area creates a shape that looks like a tooth, which doctors call the “molar tooth sign” (there is no actual tooth in the brain) [12]. In your child’s daily life, this brain malformation is what causes developmental delays, abnormal breathing patterns, and eye movement issues [11][13].
  • The Kidneys: Cells lining the tubes inside the kidneys use cilia to sense the flow of fluid [14]. Without working antennae, the kidneys may slowly develop cysts (fluid-filled sacs) or scar tissue over time [15][14].
  • The Eyes: The light-sensing cells in the back of the eye (photoreceptors) use heavily modified cilia to catch light [16]. If these structures are faulty, the cells may slowly break down. This can lead to vision loss, though the timeline and severity of this change vary significantly from child to child [17][18].
  • The Liver: Similar to the kidneys, the tiny tubes that carry bile in the liver rely on cilia to function normally [19]. Ciliary defects can lead to a buildup of scar tissue (fibrosis) in the liver over time [14][19].

What This Means For Your Child

Understanding that Joubert syndrome is a ciliopathy brings clarity to why your child’s care team looks at so many different parts of the body. They aren’t searching for unrelated problems; they are simply checking the organs known to rely heavily on these cellular antennae. Regular monitoring with specialists helps catch any kidney, liver, or eye changes early so they can be managed. This shared underlying biology is also why researchers are actively looking into therapies that might eventually help the cilia function better across the entire body [20][21].

Common questions in this guide

What exactly is a ciliopathy?
A ciliopathy is a medical condition caused by problems with primary cilia. These are tiny, hair-like structures on the surface of cells that act like cellular antennae, helping cells receive signals from their environment so organs can develop and function properly.
Why does Joubert syndrome affect so many different organs?
Joubert syndrome affects multiple organs because nearly all cells in the human body rely on primary cilia. When a genetic difference causes these cellular antennae to malfunction, it can disrupt the development and function of the brain, kidneys, eyes, and liver all at once.
What does the molar tooth sign mean in Joubert syndrome?
The molar tooth sign refers to a specific shape seen on an MRI scan when a part of the brain called the cerebellum does not fully develop. This underdeveloped area looks like a tooth on the scan and is responsible for symptoms like developmental delays and abnormal breathing patterns.
What kind of doctors will my child need to see for a ciliopathy?
Because Joubert syndrome can affect multiple systems, your child will likely need a coordinated care team. This team often includes neurologists for the brain, nephrologists for the kidneys, ophthalmologists for the eyes, and hepatologists for the liver.
How will my child's kidney and liver health be managed?
Your child's care team will schedule routine screenings and tests to monitor kidney and liver function over time. Catching early signs of cysts or scar tissue allows specialists to manage these changes proactively.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Who on my child's care team will act as the 'quarterback' to coordinate monitoring for the brain, eyes, liver, and kidneys?
  2. 2.Based on my child's specific genetic mutation, are there certain organ systems we need to monitor more closely than others?
  3. 3.How often should we schedule routine screening for kidney and liver function, and what specific tests will be used?
  4. 4.What early, noticeable signs of kidney or liver changes should I watch for at home between appointments?
  5. 5.Can you refer us to a specialized pediatric ophthalmologist who is familiar with retinal dystrophy in ciliopathies?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

Related questions

Does Joubert Syndrome Cause Blindness or Vision Loss?Does Joubert Syndrome Cause Extra Fingers or Toes?Does Joubert Syndrome Cause Hormone Problems?How Often Should Joubert Syndrome Patients Be Screened?Is COACH Syndrome the Same as Joubert Syndrome?Is General Anesthesia Safe for Joubert Syndrome?Chance of Having Another Child with Joubert SyndromeJoubert Syndrome vs Dandy-Walker: What is the Difference?What are Joubert Syndrome Related Disorders?What is the Life Expectancy for Joubert Syndrome?What is the Molar Tooth Sign in Joubert Syndrome?When Do Children With Joubert Syndrome Walk and Talk?Why Do Babies With Joubert Syndrome Breathe Abnormally?Joubert Syndrome: Why Get Genetic Testing After MRI?

References

References (21)
  1. 1

    [Targeting the ubiquitin system for treatment of cilia-related diseases].

    Nishimura Y, Inagaki M

    Nihon yakurigaku zasshi. Folia pharmacologica Japonica 2021; (156(1)):4-8 doi:10.1254/fpj.20072.

    PMID: 33390480
  2. 2

    Primary cilia function as hubs for signal transduction.

    Li B, He YY, Yang ZM

    Cell & bioscience 2025; (15(1)):163 doi:10.1186/s13578-025-01471-1.

    PMID: 41310849
  3. 3

    Primary Cilia in Cystic Kidney Disease.

    Avasthi P, Maser RL, Tran PV

    Results and problems in cell differentiation 2017; (60()):281-321 doi:10.1007/978-3-319-51436-9_11.

    PMID: 28409350
  4. 4

    Ahi1 promotes Arl13b ciliary recruitment, regulates Arl13b stability and is required for normal cell migration.

    Muñoz-Estrada J, Ferland RJ

    Journal of cell science 2019; (132(17)) doi:10.1242/jcs.230680.

    PMID: 31391239
  5. 5

    Clinical and Molecular Diagnosis of Joubert Syndrome and Related Disorders.

    Radha Rama Devi A, Naushad SM, Lingappa L

    Pediatric neurology 2020; (106()):43-49 doi:10.1016/j.pediatrneurol.2020.01.012.

    PMID: 32139166
  6. 6

    Functional genome-wide siRNA screen identifies KIAA0586 as mutated in Joubert syndrome.

    Roosing S, Hofree M, Kim S, et al.

    eLife 2015; (4()):e06602 doi:10.7554/eLife.06602.

    PMID: 26026149
  7. 7

    Establishing and regulating the composition of cilia for signal transduction.

    Nachury MV, Mick DU

    Nature reviews. Molecular cell biology 2019; (20(7)):389-405 doi:10.1038/s41580-019-0116-4.

    PMID: 30948801
  8. 8

    Spatiotemporal manipulation of ciliary glutamylation reveals its roles in intraciliary trafficking and Hedgehog signaling.

    Hong SR, Wang CL, Huang YS, et al.

    Nature communications 2018; (9(1)):1732 doi:10.1038/s41467-018-03952-z.

    PMID: 29712905
  9. 9

    Bardet-Biedl Syndrome proteins regulate cilia disassembly during tissue maturation.

    Patnaik SR, Kretschmer V, Brücker L, et al.

    Cellular and molecular life sciences : CMLS 2019; (76(4)):757-775 doi:10.1007/s00018-018-2966-x.

    PMID: 30446775
  10. 10

    Cilia-localized GID/CTLH ubiquitin ligase complex regulates protein homeostasis of sonic hedgehog signaling components.

    Hantel F, Liu H, Fechtner L, et al.

    Journal of cell science 2022; (135(9)) doi:10.1242/jcs.259209.

    PMID: 35543155
  11. 11

    Phenotypic variability in Joubert syndrome is partially explained by ciliary pathophysiology.

    Owens JW, Hopkin RJ, Martin LJ, et al.

    Annals of human genetics 2024; (88(1)):86-100 doi:10.1111/ahg.12537.

    PMID: 37921557
  12. 12

    Exome Analysis Reveals Novel Missense and Deletion Variants in the CC2D2A Gene as Causative of Joubert Syndrome.

    Cabrita Pinto RL, Viaggi S, Canale E, et al.

    Genes 2023; (14(4)) doi:10.3390/genes14040810.

    PMID: 37107568
  13. 13

    Genetics Review: Joubert Syndrome.

    Tran AM, Jnah AJ, De Castro Pretelt MJ

    Neonatal network : NN 2025; (44(3)):159-166 doi:10.1891/NN-2024-0052.

    PMID: 40537162
  14. 14

    Molecular genetics of renal ciliopathies.

    Barroso-Gil M, Olinger E, Sayer JA

    Biochemical Society transactions 2021; (49(3)):1205-1220 doi:10.1042/BST20200791.

    PMID: 33960378
  15. 15

    Renal ciliopathies.

    Devlin LA, Dewhurst RM, Sudhindar PD, Sayer JA

    Current topics in developmental biology 2025; (163()):229-305 doi:10.1016/bs.ctdb.2025.01.009.

    PMID: 40254346
  16. 16

    Review of Ocular Manifestations of Joubert Syndrome.

    Wang SF, Kowal TJ, Ning K, et al.

    Genes 2018; (9(12)) doi:10.3390/genes9120605.

    PMID: 30518138
  17. 17

    Insights Gained From Zebrafish Models for the Ciliopathy Joubert Syndrome.

    Rusterholz TDS, Hofmann C, Bachmann-Gagescu R

    Frontiers in genetics 2022; (13()):939527 doi:10.3389/fgene.2022.939527.

    PMID: 35846153
  18. 18

    Human Mutations in Arl3, a Small GTPase Involved in Lipidated Cargo Delivery to the Cilia, Cause Retinal Dystrophy.

    Travis AM, Pearring JN

    Advances in experimental medicine and biology 2023; (1415()):283-288 doi:10.1007/978-3-031-27681-1_41.

    PMID: 37440046
  19. 19

    Ttc30a affects tubulin modifications in a model for ciliary chondrodysplasia with polycystic kidney disease.

    Getwan M, Hoppmann A, Schlosser P, et al.

    Proceedings of the National Academy of Sciences of the United States of America 2021; (118(39)) doi:10.1073/pnas.2106770118.

    PMID: 34548398
  20. 20

    Toward personalized medicine in Bardet-Biedl syndrome.

    Kenny J, Forsythe E, Beales P, Bacchelli C

    Personalized medicine 2017; (14(5)):447-456 doi:10.2217/pme-2017-0019.

    PMID: 29754569
  21. 21

    Ophthalmologic Manifestations in Bardet-Biedl Syndrome: Emerging Therapeutic Approaches.

    Rosado A, Rodriguez E, Izquierdo N

    Medicina (Kaunas, Lithuania) 2025; (61(7)) doi:10.3390/medicina61071135.

    PMID: 40731764

This page explains the biology of Joubert syndrome as a ciliopathy for educational purposes. Always consult your child's pediatric care team for specific monitoring, diagnostic, and care instructions.

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