J Genet Med.  2014 Dec;11(2):69-73. 10.5734/JGM.2014.11.2.69.

Distribution of five common subtypes of spinocerebellar ataxia in the Korean population

Affiliations
  • 1Medical Genetics Center, Asan Medical Center, Seoul, Korea. hwyoo@amc.seoul.kr
  • 2Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.

Abstract

PURPOSE
Spinocerebellar ataxia (SCA) is a genetically heterogeneous disease for which more than 30 subtypes have been identified. However, 5 subtypes, SCA1, SCA2, SCA3, SCA6, and SCA7, account for more than 60% of cases. In this study, we report the distribution of these 5 subtypes in Korean patients.
MATERIALS AND METHODS
Six hundred and thirty-eight unrelated patients with a presumptive diagnosis of SCA were included in this study. Trinucleotide (CAG) repeat number (TNR) repeat number was determined using fluorescently labeled primers and fragment analysis.
RESULTS
A total of 128 unrelated patients (20.1% of all individuals tested) tested positive for SCA subtypes, including SCA1 (5 patients, 3.9% of those testing positive), SCA2 (38 patients, 29.7%), SCA3 (30 patients, 23.4%), SCA6 (39 patients, 30.5%), and SCA7 (16 patients, 12.5%). The mean copy number of pathogenic TNR alleles was 45+/-8.5 for SCA1, 42+/-3.1 for SCA2, 72+/-5.4 for SCA3, 23+/-1.5 for SCA6, and 50+/-11.4 for SCA7. TNR copy number was inversely correlated with onset age in SCA2, SCA6, and SCA7.
CONCLUSION
SCA2, SCA3, and SCA6 are common SCA subtypes in Korean patients and could be screened as a first-line test. Expanded pathogenic allele size was associated with early onset age.

Keyword

Spinocerebellar ataxias; Trinucleotide repeats
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