Spinocerebellar Ataxia Type 2 Repeat Analysis
Use
Spinocerebellar Ataxia Type 2 (SCA2) is a slowly progressive neurodegenerative disorder characterized by ataxia, dysarthria, dysphagia, oculomotor dysfunction (including nystagmus, slow saccadic eye movements, ophthalmoparesis), tremor, peripheral neuropathy, dystonia or chorea, dementia, and occasionally parkinsonism. Infantile-onset neurodevelopmental features including developmental delay, hypotonia, seizures, and cerebellar atrophy have also been reported. SCA2 is inherited in an autosomal dominant manner, caused by expansion of a CAG trinucleotide repeat in exon 1 of the ATXN2 gene, with molecular genetic testing detecting expansions in >99% of affected individuals.
Special Instructions
Uses genomic DNA from the submitted specimen. Testing employs PCR fragment analysis for ≤100 repeats and repeat‑primed PCR for >100 repeats. Evaluation of CAA interruptions is not performed. Internal standards are analyzed with clinical samples to assess assay performance. Accuracy: ±2 repeats for ≤50 repeats, ±5 repeats for 51–100 repeats; alleles >100 repeats cannot be determined exactly.
Limitations
Exact repeat number cannot be determined for alleles exceeding 100 repeats. Evaluation of CAA interruptions is not included. Somatic mosaicism may lead peripheral blood repeat sizes to differ from other tissues. Accuracy diminishes for large repeats. Interpretation must consider clinical findings, family history, and other laboratory data.
Methodology
PCR-based (PCR)
Biomarkers
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Extracted DNA
Volume
Not provided
Minimum Volume
Not provided
Other tests from different labs that may be relevant