Journal of Genetic Medicine

Korean Society of Medical Genetics and Genomics (대한의학유전학회)
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Distribution of five common subtypes of spinocerebellar ataxia in the Korean population

  • Choi, In-Hee (Medical Genetics Center, Asan Medical Center) ;
  • Kim, Gu-Hwan (Medical Genetics Center, Asan Medical Center) ;
  • Lee, Beom-Hee (Medical Genetics Center, Asan Medical Center) ;
  • Choi, Jin-Ho (Department of Pediatrics, Asan Medical Center Children’s Hospital, University of Ulsan College of Medicine) ;
  • Yoo, Han-Wook (Medical Genetics Center, Asan Medical Center)
  • Received : 2014.12.08
  • Accepted : 2014.12.10
  • Published : 2014.12.31
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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 $45{\pm}8.5$ for SCA1, $42{\pm}3.1$ for SCA2, $72{\pm}5.4$ for SCA3, $23{\pm}1.5$ for SCA6, and $50{\pm}11.4$ 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.

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References

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