Estimated occurrenceThe number of people with Joubert syndrome is unknown. In Sweden, about five children per year are born with changes in the cerebellum and lack of coordination (ataxia). One or a couple of these children probably have Joubert syndrome. Joubert syndrome is about twice as common in boys as in girls.
Changes (mutations) in about thirty genes have been linked to Joubert syndrome. Genes linked to Joubert syndrome affect the primary cilia. Joubert syndrome thus belongs to the ciliopathy diagnosis group. In most cases, Joubert syndrome has an autosomal and recessive inheritance.
Joubert syndrome is a congenital syndrome where the central part of the cerebellum is completely or partly missing. Radiography of the brain shows changes to the brain stem and that the brain stem has the form of a molar tooth, this is called the “molar tooth sign”.
There are cilia throughout the body. This means that many different parts of the body may be affected in Joubert syndrome. The syndrome varies greatly from one person to the next. Children with Joubert syndrome often have an abnormal breathing pattern during the neonatal period, low muscle tone, unsteady and jerky movement pattern (ataxia). Visual impairment (retinal dystrophy), eye jitters (nystagmus) and strabismus occur. Some people have drooping eyelids (ptosis). Kidney changes may lead to reduced kidney function. Many have a reduced ability to transport mucus. A few have liver fibrosis, hernia of the cervical spine, epilepsy, supernumerary fingers and toes (polydactyly) or an underdeveloped duodenum (duodenal atresia). Some people with Joubert syndrome have an increased risk of infection. Many, but not all, have an intellectual disability. ADHD is common, as are autistic traits. Many adults with Joubert syndrome require continued habilitation and support in their everyday life.
People with Joubert syndrome sometimes have certain common traits in their physical appearance, such as high arched eyebrows, flat nose bridge, triangular mouth and low-positioned ears.
Joubert-Boltshauser syndrome, cerebello-oculo-renal syndrome, Joubert syndrome-related disorders.
People with Joubert syndrome have an increased incidence of benign tongue polyps, various types of bite abnormalities, thick labial and lingual frenula, missing lingual frenulum and cleft palate. It has not yet been determined if dental aplasia is more common in people with Joubert syndrome. Some children have bad oral habits or engage in self-harm behaviour, such as biting their tongue, lips or hands.
Oral-motor problems often affect the ability to speak and eat, and may lead to decreased saliva control (drooling). Muscle weakness, decreased muscle tone and breathing difficulties cause many children with Joubert syndrome to have problems with eating, sucking and swallowing, mainly during the neonatal period. Many have a decreased ability to mobilize mucus and secretions in their nose and throat, which may make breathing through the nose difficult. Reflux problems are common. Most people with Joubert syndrome speak in a way that is difficult to comprehend, or do not speak at all. Oral dyspraxia, i.e. difficulties with voluntary control of oral and facial movements, which cannot be explained by paralysis or muscle weakness, is common. Apraxia may make speech unclear. Some people with Joubert syndrome have an uneven linguistic ability; they know and understand more than they are able to express. Many have reading and writing difficulties.
Sensitivity to touch in the mouth is common and may make tooth brushing and going to the dentist difficult. Other risk factors for oral hygiene include difficulties with participating in oral/dental care, eating difficulties, extensive reflux, and a reduced ability to clean the mouth themselves after a meal due to oral-motor limitations.
Advice on follow-up and treatment
- It is important that people with Joubert syndrome receive strengthened preventive dental care and oral health information at an early stage
- Benign changes to the tongue should be monitored, so as not to interfere with its function.
- In case of a palate defect, a specialist team (Cleft lip and palate team) are responsible for follow-up and treatment.
- Early interventions such as splints should be provided to prevent bite injuries in case of self-harm behaviour. Speech pathologists can provide information on sensory stimulation of the mouth and biting behaviour. Multidisciplinary cooperation is important.
- Eating and swallowing difficulties should be investigated and treated by a specialist team at a hospital (a nutrition team or dysphagia team) or habilitation.
- In case of communication difficulties, it is important to make early contact with a speech pathologists for investigation and possible treatment with language stimulation, guidance and, if required, augmentative and alternative communication (AAC).