Developed by Stephanie Bell

Joubert Syndrome

What is Joubert Syndrome?

Joubert syndrome is a rare brain malformation characterized by the absence or underdevelopment of the cerebellar vermis- an area of the brain that controls balance and coordination.This condition is characterized by a specific finding on an MRI called a "molar tooth sign" in which the cerebellar vermis of the brain is absent or underdeveloped and the brain stem is abnormal.

Most cases of Joubert Syndrome are sporadic (not inherited, no other family member has it). However, in some families, it appears to be inherited via a recessive gene where both parents have a copy of the mutation, and it is passed from parent to child.Genetic testing is not currently available to detect this condition.

The severity of the prognosis depends on whether or not the cerebellar vermis is partially developed or entirely absent. Some individuals have a mild form with minimal motor disability and good mental development, while others may have severe motor disability and moderate mental retardation.
Common features associated with this syndrome in infants include abnormally rapid breathing (hyperpnea), decreased muscle tone (hypotonia), jerky eye movements (oculomotor apraxia), mental retardation/developmental delays, and difficulty/inability to coordinate voluntary muscle movements (ataxia). Some physical deformaties such as extra fingers and toes (polydactyly), cleft lip or palate, and tongue abnormalities may also be present.
Effects on the Visual System

The following features may be present in some individuals: rapid, involuntary movements of the eye (nystagmus), severe visual impairment with blindness or near-blindness in both eyes (Leber’s congenital amaurosis), retinal dystrophy (particularly flattened electroretinogram/ERG or increased pigmentation of the retina in which there is progressive retinal degeneration in both eyes), and a malformation of the retina or other regions of the eye (coloboma). More often present is Oculomotor apraxia (OMA), in which a specific eye movement abnormality makes it difficult for children to track objects smoothly (eyes may appear to jump with jerky eye movements).
Treatment Options

Presently, there is no cure for Joubert syndrome. Treatment for infants and children is symptomatic and supportive and may include stimulation and physical, occupational, and speech therapy. Infants with abnormal breathing patterns should be monitored, and screening for progressive eye, liver, and kidney complications associated with the disorder is recommended to be done on a regular basis.

Sources

  1. Cassin, B., & Rubin, M.L., M.D., Editor (2006). Dictionary of Eye Terminology,5th Ed.(pp. 148, 159, 186). Gainesville, FL: Triad Publishing Company.
  2. Joubert Syndrome Foundation and Related Cerebellar Disorders. (1992). Website:
  3. The Cleveland Clinic: Joubert Syndrome. (1995). Website:
  4. National Institute of Neurological Disorders and Stroke. NINDS Joubert Syndrome Information Page. Website:
  5. National Organization of Rare Disorders: Joubert Syndrome. (2006). Website:
  6. Goldberg, S., M.D. (1996). Ophthalmology Made Ridiculously Simple (pp 37, 42, 72, 77). Miami, FL: MedMaster, Inc.