Also known as: Joubert-Boltshauser syndrome
Joubert syndrome is a rare neurological condition characterised by developmental delay, floppiness (see entry Hypotonia), ataxia (lack of muscle control) and difficulty controlling oculomotor apraxia (horizontal eye movements). Other symptoms include hyperpnea (abnormal breathing patterns), kidney abnormalities (see entry Kidney disease) and a characteristic facial appearance. Individuals with Joubert syndrome may show some or all of these features and their severity may vary. The major investigation finding is underdevelopment of the cerebellar vermis (a narrow, worm-like structure between the hemispheres of the cerebellum) and brain stem on a magnetic resonance imaging (MRI) scan.
Medical text written May 2003 by Contact a Family. Approved May 2003 by Professor M Patton, Professor of Medical Genetics, St George’s Hospital Medical School, London, UK. Last updated February 2010 by Professor Brian Neville, Emeritus Professor of Paediatric Neurology, UCL Institute of Child Health and Great Ormond Street Hospital, London, UK.
Hypotonia is particularly evident in the neonatal period (the period immediately after birth) and during infancy. Children may be moderately or severely affected and may lack head control, have difficulties rolling over, sitting, standing and walking. Unsteadiness due to ataxia and balance problems may also be present. Joubert syndrome also affects breathing and abnormal over breathing commonly occurs during the neonatal period. This may improve with age but, in some cases, it persists and may threaten survival.
Individuals with Joubert syndrome have abnormal eye movements including a squint with or without retinal degeneration, and with or without congenital blindness (see entry Vision disorders in Childhood). Young infants with Joubert syndrome often have a characteristic appearance with a large head, prominent forehead, high rounded eyebrows, broad nasal ridge, mild epicanthus, upturned nose with evident nostrils, open mouth and protruding tongue. This appearance becomes less pronounced as the child grows.
Cognitive and physical development is delayed in Joubert syndrome. Moderate-to-severe learning difficulties are common, language may be delayed. Some children with Joubert syndrome are hyperactive, combative and difficult to manage whilst others display normal behaviour.
Joubert syndrome may be caused by gene abnormalities in at least three ‘loci’ or specific locations on a gene that relate to subtypes of Joubert syndrome. Some have no identifiable gene defect. The cerebellar vermis is responsible for controlling posture, coordinating head and eye movements and fine-tuning muscles. The brain stem is responsible for maintaining the body’s involuntary functions, such as heartbeat, breathing, and thermoregulation. The cerebellar vermis and brain stem are underdeveloped or absent in individuals with Joubert syndrome. These changes may be identified on an magnetic resonance imaging (MRI) scan of the brain.
Treatment for Joubert syndrome is symptomatic (designed to alleviate the symptoms experienced by an individual with the condition) and supportive. Infant stimulation, physical, occupational, and speech therapy may have beneficial effects.
Joubert syndrome is inherited as an autosomal recessive trait.
Features of Joubert syndrome may sometimes be visualised by ultrasound scan by 18 to 20 weeks of pregnancy. If a specific gene defect is known, it can be identified.