Joubert syndrome is disorder of brain development that may affect many parts of the body. It is characterized by the absence or underdevelopment of the cerebellar vermis (a part of the brain that controls balance and coordination) and a malformed brain stem (connection between the brain and spinal cord). Together, these cause the characteristic appearance of a molar tooth sign on MRI. Signs and symptoms can vary but commonly include weak muscle tone (hypotonia); abnormal breathing patterns; abnormal eye movements; ataxia; distinctive facial features; and intellectual disability. Various other abnormalities may also be present. Joubert syndrome may be caused by mutations in any of many genes. Inheritance is usually autosomal recessive, but rarely it may be X-linked recessive. Treatment is supportive and depends on the symptoms in each person.
Last updated: 11/29/2016
What are the signs and symptoms of Joubert syndrome?
Most infants with Joubert syndrome have weak muscle tone (hypotonia), which evolves into difficulty coordinating movements (ataxia) in early childhood. Affected children may have episodes of unusually fast or slow breathing (hyperpnea), which tends to occur shortly after birth. This may intensify with emotional stress, but progressively improves with age and usually disappears around 6 months of age.
Abnormal eye movements are also common. Oculomotor apraxia occurs frequently and causes difficulty moving the eyes from side to side. People with oculomotor apraxia have to turn their heads to see things in their peripheral vision.
Developmental abilities, in particular language and motor skills, are delayed with variable severity. Mild to severe intellectual disability is common, but some people with Joubert syndrome have normal intellectual abilities.
Distinctive facial features are also characteristic. These include a broad forehead, arched eyebrows, droopy eyelids (ptosis), widely spaced eyes, low-set ears, and a triangular-shaped mouth.
Joubert syndrome can cause a wide range of additional signs and symptoms. The condition is sometimes associated with other eye abnormalities (such as retinal dystrophy, which can cause vision loss); kidney disease; liver disease; skeletal abnormalities (such as extra fingers and toes); and hormone (endocrine) problems. When the characteristic features of Joubert syndrome occur with one or more of these additional features, researchers refer to the condition as "Joubert syndrome and related disorders (JSRD)" or as a subtype of Joubert syndrome.
Last updated: 11/29/2016
Is there a connection between Joubert syndrome and autism?
There is a connection, but it remains somewhat unclear. Autism is a relatively common condition, occurring in 1 in 500 children, and is more likely in boys with a 4:1 male:female ratio. There are likely many different causes for this increasingly common diagnosis. Features of classical autism include poor eye contact and limited communication skills as well as repetitive or self-stimulatory behaviors. Autism has been reported in a number of children with Joubert syndrome in several publications. However, more recent surveys suggest that these behavioral disturbances do not represent classic autism, but are more likely to be related to the underlying cerebellar disorder, eye movement problems, and associated developmental disabilities.  You can read more about the question of whether there is a connection between Joubert syndrome and autism on the University of Washington School of Medicine's Joubert Research Program's Web site. Click on the link to view their frequently asked questions.
Last updated: 2/10/2011
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