Joubert Syndrome (JBTS)

Joubert Syndrome is a rare developmental disorder affecting mainly the brain but might be accompanied by renal and/or retinal symptoms. Mutations in several genes associated with cilia can cause Joubert Syndrome and are inherited often in a autosomal-recessive manner but x-chromosomal-recessive inheritance also occurs.

Primary features

  • Abnormalities of the brain, mainly the cerebellum-part lead to low muscle tonus at birth, developmental delay and can cause breathing abnormalities and movement disorders.
  • Brain scans such as magnetic resonance tomography (MRI) show a pathognomic picture named “molar tooth sign”.
  • Renal disease, usually in the form of Nephronophthisis, may also occur and can lead to renal insufficiency.
  • Retinal degeneration is observed in some patients (often in combination with kidney disease) and can present initially as night blindness, progressing into visual loss also in daylight and blindness.
  • Extra fingers and toes (Polydactyly) is sometimes observed.


  • There is a broad phenotypic spectrum of the brain phenotype among patients ranging from developmental delay and slight movement problems to severe brain defects including open brain that might be incompatible with life.
  • Breathing problems are due to cerebral mis-regulation rather than to primary problems in the respiratory tract and can lead to death.
  • No cure is currently available for Joubert Syndrome, only supportive therapy.

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NCB/NIH/PubMed references

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