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PubMed This is a summary of 24 peer-reviewed journal articles Updated
Joubert syndrome

What are Joubert Syndrome Related Disorders?

At a Glance

Classic Joubert syndrome affects only the brain, featuring a hallmark MRI shape called the molar tooth sign. 'Related disorders' occur when this genetic condition also impacts other organs, such as the kidneys, liver, or eyes, requiring specialized long-term monitoring for your child.

In this answer

3 sections

01

The Molar Tooth Sign: The Shared Link

02

What Are the “Related Disorders”?

03

Why Does It Vary So Much?

When doctors use the term “Joubert syndrome and related disorders” (often shortened to JSRD), they are acknowledging that Joubert syndrome is not just a single condition, but a spectrum [1]. The main difference comes down to which parts of the body are affected. “Pure” or classic Joubert syndrome typically involves only the brain and neurological development [1][2]. The phrase “related disorders” is added when the condition also affects other organs in the body, most commonly the kidneys, liver, eyes, or bones [3][4]. No matter which specific organs are involved, everyone on this spectrum shares the same underlying hallmark feature: a specific brain malformation known as the molar tooth sign [5][6].

Whether a child has pure Joubert syndrome or a related disorder, the common thread is the molar tooth sign (MTS) [7][8]. This is a unique shape seen on a brain MRI. It happens when the part of the brain that controls balance and coordination (the cerebellar vermis) is underdeveloped, and the nerve fibers connecting different parts of the brain stem are thicker and longer than usual [9][10]. Because it looks like the root of a tooth on a brain scan, it is called the “molar tooth sign.” This shared brain feature is why these conditions are grouped together, causing similar neurological challenges like low muscle tone (hypotonia), breathing abnormalities in infancy (such as short periods of very fast breathing or breath-holding, which your care team can help monitor), developmental delays, and unusual eye movements [1][5].

Joubert syndrome is a type of ciliopathy [3][11]. This means it is caused by a problem with the primary cilia—tiny, hair-like structures found on almost every cell in the human body. Because primary cilia are everywhere, their malfunction can affect many different organs [4].

When a child has a “related disorder,” it means the ciliary defect has impacted other systems beyond the brain. This multi-organ involvement can include:

  • Kidneys: Some children develop cysts or a specific type of chronic kidney disease called nephronophthisis [12][13].
  • Eyes: Problems with the retina (the light-sensitive layer at the back of the eye) can cause vision loss or blindness, a condition called retinal dystrophy [14][15].
  • Liver: Scarring of the liver (hepatic fibrosis) can occur in some individuals [16][1].
  • Bones: Some children are born with extra fingers or toes (usually an extra digit next to the pinky finger or toe), known as polydactyly [17][4].

Why Does It Vary So Much?

The spectrum exists because Joubert syndrome can be caused by mutations in dozens of different genes [18][19]. The specific gene that is altered often determines whether a child will have classic Joubert syndrome or a related disorder [12]. For example, mutations in certain genes (like CEP290, TMEM67, or AHI1) are more likely to cause kidney issues [12][20], while mutations in other genes may only affect the brain [13].

Understanding where your child falls on this spectrum is critical because some of these related organ issues—like kidney disease or liver scarring—may not show up until later in life [21][22]. Knowing the specific gene involved can help your care team know exactly which organs to monitor as your child grows [12][22]. You can ask your doctor or a genetic counselor about a comprehensive genetic testing panel to help identify your child’s specific gene and guide their long-term screening plan [23][24].

Common questions in this guide

What is the molar tooth sign in Joubert syndrome?
The molar tooth sign is a unique shape seen on a brain MRI that resembles the root of a tooth. It is caused by the underdevelopment of the cerebellar vermis and thickened nerve fibers. This brain feature is the hallmark sign present in everyone with Joubert syndrome.
Why does Joubert syndrome sometimes affect the kidneys or liver?
Joubert syndrome is a ciliopathy, meaning it involves defects in primary cilia, which are tiny hair-like structures found on cells throughout the body. When these defects impact organs outside the brain, such as the kidneys or liver, it is called a related disorder.
What is pure or classic Joubert syndrome?
Pure or classic Joubert syndrome typically involves only the brain and neurological development. Children with this form will have the hallmark molar tooth sign on an MRI but do not have other organ involvement like kidney disease or vision loss.
How do doctors know which organs Joubert syndrome will affect?
The specific organs affected often depend on the exact gene mutation causing the condition. Comprehensive genetic testing can identify your child's specific altered gene, helping doctors anticipate which organs need long-term monitoring as they grow.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Has a comprehensive genetic panel been completed to identify the specific gene mutation causing my child's Joubert syndrome?
  2. 2.Based on my child's genetic results and clinical picture, which specific organs (kidneys, liver, eyes) should we be monitoring right now?
  3. 3.What routine screenings (such as kidney ultrasounds or specialized eye exams) do you recommend, and how often should they be scheduled?
  4. 4.Can you refer us to a pediatric ophthalmologist, nephrologist, or hepatologist experienced with 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?What Is a Ciliopathy & How Does It Cause Joubert Syndrome?Chance of Having Another Child with Joubert SyndromeJoubert Syndrome vs Dandy-Walker: What is the Difference?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 (24)
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    Joubert Syndrome with Orofacial Digital Features.

    Bhardwaj P, Sharma M, Ahluwalia K

    Journal of neurosciences in rural practice 2018; (9(1)):152-154 doi:10.4103/jnrp.jnrp_338_17.

    PMID: 29456362
  2. 2

    A Case of Joubert Syndrome with Chronic Kidney Disease.

    Shamsudheen MP, Das U, Taduri G, et al.

    Indian journal of nephrology 2021; (31(1)):61-63 doi:10.4103/ijn.IJN_287_19.

    PMID: 33994691
  3. 3

    Whole exome sequencing identified a novel missense alteration in CC2D2A causing Joubert syndrome 9 in a Pakhtun family.

    Khan MI, Latif M, Saif M, et al.

    The journal of gene medicine 2021; (23(1)):e3279 doi:10.1002/jgm.3279.

    PMID: 32989887
  4. 4

    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
  5. 5

    Whole exome sequencing reveals novel CEP104 mutations in a Chinese patient with Joubert syndrome.

    Luo M, Cao L, Cao Z, et al.

    Molecular genetics & genomic medicine 2019; (7(12)):e1004 doi:10.1002/mgg3.1004.

    PMID: 31625690
  6. 6

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

    Stephen J, Vilboux T, Mian L, et al.

    Human genetics 2017; (136(4)):399-408 doi:10.1007/s00439-017-1765-z.

    PMID: 28220259
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    AN UNUSUAL PRESENTATION OF JOUBERT SYNDROME AND RELATED DISORDERS IN A NEWBORN: PANHYPOPITUITARISM.

    Erol S, Demirel N, Bas AY, et al.

    Genetic counseling (Geneva, Switzerland) 2016; (27(3)):367-371.

    PMID: 30204965
  8. 8

    Diagnosis of Joubert syndrome via ultrasonography.

    Buke B, Canverenler E, İpek G, et al.

    Journal of medical ultrasonics (2001) 2017; (44(2)):197-202 doi:10.1007/s10396-016-0751-8.

    PMID: 27785575
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    Smoothened and ARL13B are critical in mouse for superior cerebellar peduncle targeting.

    Suciu SK, Long AB, Caspary T

    Genetics 2021; (218(4)) doi:10.1093/genetics/iyab084.

    PMID: 34132778
  10. 10

    Joubert Plus syndrome in a child with Dandy-Walker malformation and occipital cephalocele: A case report.

    Mehari TH, Tessema BM, Gebrekidan RG

    Radiology case reports 2025; (20(9)):4701-4705 doi:10.1016/j.radcr.2025.05.103.

    PMID: 40677886
  11. 11

    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
  12. 12

    Prospective Evaluation of Kidney Disease in Joubert Syndrome.

    Fleming LR, Doherty DA, Parisi MA, et al.

    Clinical journal of the American Society of Nephrology : CJASN 2017; (12(12)):1962-1973 doi:10.2215/CJN.05660517.

    PMID: 29146704
  13. 13

    Non-classic splicing mutation in the CPLANE1 (C5orf42) gene cause Joubert syndrome in a fetus with severe craniocerebral dysplasia.

    Zhu H, Chen W, Ren H, et al.

    European journal of medical genetics 2021; (64(6)):104212 doi:10.1016/j.ejmg.2021.104212.

    PMID: 33794348
  14. 14

    Case Report: Identification of likely recurrent CEP290 mutation in a child with Joubert syndrome and cerebello-retinal-renal features.

    Spahiu L, Sayer JA, Behluli E, et al.

    F1000Research 2022; (11()):388 doi:10.12688/f1000research.109628.2.

    PMID: 37224330
  15. 15

    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
  16. 16

    Persistent left superior vena cava discovered during central line insertion in a patient with Joubert syndrome: a case report.

    Heyba MIM, Gadelrab MRMA, Ahmed WA

    Journal of medical case reports 2025; (19(1)):512 doi:10.1186/s13256-025-05573-9.

    PMID: 41094582
  17. 17

    Prenatal Diagnosis of Joubert Syndrome 23 With Left Isomerism: A Novel Phenotype Associated With Pathogenic KIAA0586 Variant.

    Casteleyn T, Vogt M, Weichert A, et al.

    Prenatal diagnosis 2025; (45(13)):1783-1786 doi:10.1002/pd.70008.

    PMID: 41148001
  18. 18

    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
  19. 19

    Novel Pathogenic Biallelic Variants in KIAA0586 Expand the Variant Spectrum of Ciliopathies.

    Shen Y, He R, Lu C, et al.

    Cytoskeleton (Hoboken, N.J.) 2025; doi:10.1002/cm.70047.

    PMID: 41020477
  20. 20

    TMEM67 mutations found in a case of Joubert syndrome with renal hypodysplasia.

    Komatsu Y, Suzuki T, Tsurusaki Y, et al.

    CEN case reports 2016; (5(2)):137-140 doi:10.1007/s13730-015-0210-1.

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  21. 21

    Joubert syndrome diagnosed renally late.

    Collard E, Byrne C, Georgiou M, et al.

    Clinical kidney journal 2021; (14(3)):1017-1019 doi:10.1093/ckj/sfaa007.

    PMID: 33777383
  22. 22

    Joubert Syndrome in Children-A Comprehensive Analysis of Quality of Life, Functional Independence and Family Impact.

    Elmaoğlu E, Coşkun AB, Usgu S, et al.

    American journal of medical genetics. Part A 2025; (197(12)):e64213 doi:10.1002/ajmg.a.64213.

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  23. 23

    Severe Joubert syndrome in family with homozygous POC1B p.Arg106Pro variant is due to a co-inherited deep-intronic mutation in the neighboring CEP290 gene.

    Betz C, Reusch B, Langmann T, et al.

    HGG advances 2025; (6(3)):100429 doi:10.1016/j.xhgg.2025.100429.

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    Exome sequencing and RNA analysis identify two novel CPLANE1 variants causing Joubert syndrome.

    Fei H, Wu Y, Wang Y, Zhang J

    Molecular genetics & genomic medicine 2022; (10(3)):e1877 doi:10.1002/mgg3.1877.

    PMID: 35092359

This page explains the differences between Joubert syndrome and related disorders for educational purposes. Always consult your child's pediatric specialist or genetic counselor for specific screening and care recommendations.

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