Joubert syndrome is a disorder that affects many parts of the body. The signs and symptoms of this condition vary among affected individuals, even among members of the same family.
The hallmark feature of Joubert syndrome is a brain abnormality called the molar tooth sign, which can be seen on brain imaging studies such as magnetic resonance imaging (MRI). This sign results from the abnormal development of regions near the back of the brain called the cerebellar vermis and the brainstem. The molar tooth sign got its name because the characteristic brain abnormalities resemble the cross-section of a molar tooth when seen on an MRI.
Most infants with Joubert syndrome have weak muscle tone (hypotonia) in infancy, which evolves into difficulty coordinating movements (ataxia) in early childhood. Other characteristic features of the condition include episodes of unusually fast or slow breathing in infancy and abnormal eye movements. Most affected individuals have delayed development and intellectual disability, which range from mild to severe. Distinctive facial features are also characteristic of Joubert syndrome; these include a broad forehead, arched eyebrows, droopy eyelids (ptosis), widely spaced eyes, low-set ears, and a triangle-shaped mouth.
Joubert syndrome can include a broad 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 the presence of extra fingers and toes), and hormone (endocrine) problems. When the characteristic features of Joubert syndrome occur in combination with one or more of these additional signs and symptoms, researchers refer to the condition as "Joubert syndrome and related disorders (JSRD)."
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Joubert syndrome - Genetics Home Reference
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