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Any Joubert syndrome in which the cause of the disease is a mutation in the B9D1 gene.
Features include always present findings: Global developmental delay, Low muscle tone (hypotonia), Ataxia, and Oculomotor apraxia and others; and common findings: Axial hypotonia, Dilatation of the renal pelvis, Gait ataxia, and Esodeviation and others. 15 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 4 | Gait ataxia, Global developmental delay, Ataxia |
B9D1 encodes B9 domain containing 1 (204 aa). Component of the tectonic-like complex, a complex localized at the transition zone of primary cilia and acting as a barrier that prevents diffusion of transmembrane proteins between the cilia and plasma membranes. Highest expression in Testis (47.0 TPM) and Pituitary (39.0 TPM).
Joubert syndrome 27 is associated with mutations in the B9D1 gene on chromosome 17.
B9D1 is classified as a druggable target with score 0.0.
Genetic testing for B9D1 is available. Testing is considered confirmatory for diagnosis.
Phenotype severity distribution: 6 always present features, 8 common features.
No clinical trials have been registered for Joubert syndrome 27.
8 publications have been identified in PubMed for Joubert syndrome 27. Research spans Basic Science / Preclinical (75%), Review / Meta-Analysis (13%), and Case Report / Case Series (13%).
Liu Y (2026). [PMID: 41518077](https://pubmed.ncbi.nlm.nih.gov/41518077/). *Genesis (New York, N.Y. : 2000)*. [Basic Science / Preclinical]
He R (2026). [PMID: 41165761](https://pubmed.ncbi.nlm.nih.gov/41165761/). *The Journal of clinical investigation*. [Basic Science / Preclinical]
Campobasso G (2025). [PMID: 40565534](https://pubmed.ncbi.nlm.nih.gov/40565534/). *Genes*. [Review / Meta-Analysis]
Yang Q (2025). [PMID: 41317100](https://pubmed.ncbi.nlm.nih.gov/41317100/). *Molecular genetics & genomic medicine*. [Basic Science / Preclinical]
Carpenter EH (2025). [PMID: 40621737](https://pubmed.ncbi.nlm.nih.gov/40621737/). *Journal of cell science*. [Case Report / Case Series]
Data assembled from 5 of 12 sources · Last updated Sep 19, 2026, 3:46 PM UTC
Online Mendelian Inheritance in Man
Genetic and Rare Diseases Info Center
Common questions about Joubert syndrome 27
Muscles |
2 |
Axial hypotonia, Low muscle tone (hypotonia) |
Eyes | 2 | Oculomotor apraxia, Damage to the retina (retinopathy) |
Head and neck | 2 | Thick lower lip vermilion, Triangular face |
Kidneys and urinary system | 1 | Dilatation of the renal pelvis |
Orlova M (2024). [PMID: 39092430](https://pubmed.ncbi.nlm.nih.gov/39092430/). *Frontiers in genetics*. [Basic Science / Preclinical]
Kim HM (2024). [PMID: 38669389](https://pubmed.ncbi.nlm.nih.gov/38669389/). *Medicine*. [Basic Science / Preclinical]