Dentatorubral‑Pallidoluysian Atrophy Repeat Analysis
Use
Dentatorubral‑pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder caused by expansion of a CAG trinucleotide repeat in exon 5 of the ATN1 gene. Clinical presentation varies by age of onset with juvenile-onset featuring ataxia, myoclonus, seizures, and intellectual deterioration, and adult-onset presenting with ataxia, choreoathetosis, dementia, and psychiatric symptoms. The test analyzes the CAG repeat region in ATN1 to distinguish normal, mutable normal, incompletely penetrant, and pathogenic allele ranges, assisting in diagnosis, prognosis, and family counseling. Anticipation is a known phenomenon for this repeat expansion disorder. (Based on GeneDx test method documentation)
Special Instructions
Not provided.
Limitations
Accuracy of repeat sizing: fragment analysis provides ±2 repeats for sizes ≤50 and ±5 repeats for 51–100; alleles >100 repeats cannot have exact repeat number determined by this test. Southern blot, required for >100 repeats, is not performed as part of this assay. Clinical interpretation must consider incomplete penetrance for alleles of 36–47 repeats and often anticipatory expansion in transmission, especially paternal. Technical sensitivity depends on phenotype but all pathogenic expansions are detectable with fragment analysis; internal standards used to assure performance.
Methodology
PCR-based (PCR)
Biomarkers
No genes
Gene
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
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