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Joubert's syndrome: new cases and review of clinicopathologic correlation
L Sztriha1, L I Al-Gazali, G R Aithala
1Department of Pediatrics, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al Ain.
Insights
Joubert syndrome is a rare genetic disorder characterized by severe developmental delay and abnormal eye movements. Brain imaging reveals specific cerebellar and brainstem malformations, potentially explaining these neurological deficits.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- Joubert syndrome is a rare ciliopathy affecting brain development.
- Key features include developmental delay, hypotonia, and abnormal eye movements.
- Cerebellar vermis hypoplasia is a common finding.
Purpose of the Study:
- To investigate the neuroimaging findings in Joubert syndrome.
- To correlate radiological features with clinical symptoms.
- To explore the potential role of genetic patterning in midbrain-hindbrain development.
Main Methods:
- Retrospective analysis of seven patients with Joubert syndrome.
- Comprehensive evaluations including developmental, neurological, and ophthalmologic assessments.
- Magnetic resonance imaging (MRI) of the brain to detail structural abnormalities.
Main Results:
- All patients exhibited severe developmental delay, hypotonia, and impaired eye movements.
- Consistent findings included absence of the posterior vermis and malformation of the pontomesencephalic junction.
- Abnormal cerebellar-brainstem connections and cerebellar dysplasia were observed.
Conclusions:
- Specific structural brain abnormalities in Joubert syndrome correlate with clinical manifestations.
- The lack of the posterior vermis and cerebellar dysplasia may cause abnormal eye movements and developmental delay.
- Abnormal midbrain-hindbrain patterning during embryonic development, possibly influenced by homeotic genes, is implicated.
Abstract:
The authors report on seven patients, six males and one female, with Joubert's syndrome who underwent developmental evaluation, neurologic and ophthalmologic examinations, and magnetic resonance imaging of the brain. All patients had severe developmental delay, hypotonia, impairment of smooth visual pursuit, and saccadic eye movements. Six had jerky eye movements and ptosis was observed in two patients and retinal dystrophy in one. The posterior lobe of the vermis was absent in all patients and the small rudimentary anterior lobe lacked fusion in the midline, with cleft formation in five patients. Malformation of the pontomesencephalic junction, with prominent superior cerebellar peduncles and deep interpeduncular fossa, was observed in all patients. Abnormal cerebellar-brainstem and cerebellocortical connections because of the lack of the posterior vermis and dysplasia of the deep cerebellar nuclei might be responsible for the abnormal eye movements and retarded development in Joubert's syndrome. Correlation between radiologic findings and clinical symptoms and the possible role of abnormal patterning of the midbrain-hindbrain by homeotic genes during embryonic development are reviewed.