Spinocerebellar ataxia type 2 (SCA2) presenting with ophthalmoplegia and developmental delay in infancy

Area of Science:

• Neuroscience
• Genetics
• Pediatric Neurology

Background:

• Spinocerebellar ataxia type 2 (SCA2) typically manifests in adulthood with specific CAG repeat counts in the SCA2 gene.
• Infantile-onset SCA2 is rare, with limited clinical descriptions and often associated with a significantly higher number of CAG repeats.

Observation:

• An 11-year-old boy presented with early-onset progressive ataxia, cognitive deterioration, and ophthalmoplegia, starting with abnormal eye movements at 2 months.
• Neurological examination revealed external ophthalmoplegia, ataxic dysarthria, upper extremity tremor, and severe gait ataxia.
• Brain MRI showed significant cerebellar, brainstem, and cerebral atrophy. Genetic analysis identified 62 CAG repeats in one allele of the SCA2 gene.

Findings:

• The patient's clinical presentation and genetic findings represent a novel description of childhood-onset SCA2.
• The number of CAG repeats (62) falls below the typical range for adult-onset SCA2 but is significantly lower than reported neonatal cases (>200 repeats).

Implications:

• This case expands the phenotypic spectrum of SCA2, particularly for infantile-onset forms.
• Highlights the importance of considering SCA2 in the differential diagnosis of pediatric patients presenting with progressive ataxia and neurodevelopmental issues.
• Suggests that CAG repeat length in SCA2 may not strictly correlate with age of onset or severity across all pediatric cases.