SYMPTOMS:
What is Joubert Syndrome?
Joubert syndrome is a rare, genetic disorder that affects the area of the brain that controls balance and coordination. The
disorder is characterized by absence or underdevelopment of a part of the brain called the cerebellar vermis and a
malformed brain stem. The most common features include ataxia (lack of muscle control), an abnormal breathing pattern
called hypernea, sleep apnea, abnormal eye and tongue movements, and hypotonia. Other malformations such as extra fingers
and toes, cleft lip or palate, tongue abnormalities, and seizures may also occur. There may be mild or moderate developmental delays or mental retardation.
Joubert Syndrome and Related Disorders are a group of developmental brain disorders characterized clinically by disturbances
of breathing rhythm, ataxia, oculomotor abnormalities, developmental delays, and hypotonia. These disorders are
characterized on brain imaging by cerebellar vermis hypoplasia and the "molar-tooth" sign of the brainstem. From our
review of clinical records from patients in the Joubert Syndrome Foundation, we have found many with co-existing medical
conditions at a frequency sufficient to warrant a set of guidelines for the evaluation and monitoring of all patients with
Joubert Syndrome and Related Disorders. These evaluations are necessary for two reasons. First is for proper diagnosis of
the child, as we find that approximately 20% of patients display features indicating a subtype of Joubert syndrome or a
related syndrome. Second is to try to prevent medical complications from these associated conditions, which through proper
screening might be avoided. However, because our total knowledge of Joubert syndrome and its complications are limited, our
recommendations will need to be evaluated and changed as new information becomes available.
For a summary of the genetics of Joubert syndrome and a web-based summary of the condition please go to the GeneReview entry.
Patients with Joubert Syndrome and Related Disorders, in addition to the features mentioned above, have displayed the
following features:
1. Abnormal electroretinogram, indicating co-existent retinal dysplasia and visual impairment.
2. Optic colobomas, which may also limit vision.
3. Kidney disease, which may include juvenile nephronophthisis or cystic dysplastic kidneys. In some patients, the kidney
disease has progressed to end-stage renal failure that required dialysis or transplantation.
4. Liver fibrosis with or without compromised liver function.
5. Tongue tumors (hamartomas), enlarged tongues, multiple frenulae or other unusual anomalies of the mouth.
6. Polydactyly of fingers or toes that may be simple or complex.
7. Hypothalamic disorders, sometimes related to a hypothalamic hamartoma.
8. Additional subtle variation in the appearance of brain structures, including polymicrogyria or encephalocele.
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