Neurodevelopmental Progression and Functional Outcomes in a Child With Joubert Syndrome: A Case Study.

Joubert syndrome (JS) is a rare autosomal recessive neurodevelopmental disorder characterized by malformations of the cerebellum and brainstem, most notably the pathognomonic "molar tooth sign" on magnetic resonance imaging (MRI). Clinical manifestations are heterogeneous and include dysmorphic features, motor and ocular abnormalities, and, in most patients, intellectual developmental disorder (IDD). We describe the case of a nine-year-old boy with prenatal suspicion of ventricular asymmetry and postnatal findings of macrocephaly and facial dysmorphisms. In infancy, he exhibited nystagmus, oculomotor apraxia, irregular breathing, ataxia, and delayed motor milestones; MRI at 18 months revealed cerebellar vermis hypoplasia with a "molar tooth sign," supporting the diagnosis of JS despite the absence of a causative variant in extended genetic testing. Over time, motor and coordination deficits improved with sustained physical and occupational therapy, complemented by school and family support. Cognitive abilities remained within the expected range, although expressive language delay and motor coordination difficulties were present. At the age of eight years, he was diagnosed with attention-deficit/hyperactivity disorder, inattentive subtype, and responded well to methylphenidate, with marked improvements in attention, concentration, handwriting, and academic performance. This case illustrates a milder neurological phenotype of JS with preserved learning abilities, emphasizing the importance of MRI in diagnosis and highlighting the benefit of early individualized rehabilitation and targeted treatment of comorbidities. It also underscores the role of genetic counseling, although no pathogenic variants were identified, reflecting the syndrome's genetic diversity.