Cognitive, adaptive, and behavioral features in Joubert syndrome

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• Joubert syndrome (JS) is a rare, recessive neurodevelopmental disorder.
• Characterized by cerebellar and brainstem malformations (molar tooth sign).
• The full spectrum of cognitive and behavioral phenotypes in JS remains poorly understood.

Purpose of the Study:

• To define the clinical phenotype and neurobehavioral characteristics of a large cohort of individuals with JS.
• To investigate the variability in cognitive functioning and behavioral profiles.
• To assess the long-term outcomes and impact on daily living skills.

Main Methods:

• Multicenter study involving 54 patients diagnosed with JS.
• Age range: 10 months to 29 years.
• Comprehensive assessments including neurological evaluation, psychiatric, and neuropsychological evaluations.

Main Results:

• Global cognitive functioning showed significant variability (IQ 32-129).
• Motor domain was the most vulnerable area, impacting daily living and academic skills.
• Communication skills were relatively preserved compared to socialization and daily living abilities.
• Approximately 40% experienced emotional and behavioral problems, though most did not meet criteria for psychiatric diagnosis.
• Nearly 25% had favorable long-term outcomes with normal or borderline cognitive function.

Conclusions:

• Intellectual disability is common in JS but not a mandatory diagnostic criterion.
• JS presents a wide phenotypic spectrum with variable multiorgan involvement.
• Despite challenges, many individuals with JS exhibit preserved communication and discrete behavioral functioning in daily life, irrespective of intellectual disability level.