Joubert syndrome is a genetic disorder that affects many different parts of the body. The most common finding in people with Joubert syndrome is the underdevelopment of an area in the brain that controls balance and coordination (cerebellar vermis). This underdeveloped area is called a molar tooth sign because it looks like a molar tooth when viewed on a brain MRI. In addition to this brain finding, most people with Joubert syndrome have weak muscle tone (hypotonia) in infancy, poor coordination (ataxia), unusually fast breathing, abnormal eye movements, and developmental delays. People with Joubert syndrome may also have a broad forehead, arched eyebrows, droopy eyelids (ptosis), widely spaced eyes, low-set ears, and a triangle-shaped mouth.
Other symptoms of Joubert syndrome that are less common include eye abnormalities, kidney problems, liver disease, skeletal abnormalities (extra fingers and toes), and problems with hormone function. The signs and symptoms of Joubert syndrome can vary from person to person, even between members in the same family. Joubert syndrome is usually inherited in an autosomal recessive manner. Mutations (changes) in multiple genes are associated with Joubert syndrome. These genes provide instructions for making cilia, little finger like projections on the outside of cells that are important for cell signaling and communication. A person with mutations in a cilia gene cannot make normal cilia (called a ciliopathy).
Joubert syndrome is typically diagnosed when a person has a brain MRI that shows a molar tooth sign. Genetic testing may be necessary to confirm the diagnosis. There is no cure for Joubert syndrome, but there are treatments that can address the symptoms. If your child has been diagnosed with Joubert syndrome, talk with your doctor about the most current treatment options. Meeting with genetic counselor or specialist may be helpful. Support groups are also a good resource.