CAG repeat expansion in the SCA7 in Korean families presenting clinical features compatible with ADCA type II

ABSTRACT

BACKGROUND: Autosomal dominant cerebellar ataxia type II(ADCA type II) can be differentiated from other types of ADCA by visual disturbances due to pigmentary macular degeneration. Recent genetic studies repeatedly mapped the gene responsible for ADCA type II to chromosome 3p12-13(SCA7) in caucasian patients. However, in Asian patients CAG expansion at the SCA7 locus has not yet been reported. METHODS: We analyzed clinical data obtained from three Korean families in which 14 members presented clinical features compatible with ADCA type II. We also performed a genetic study for 17 members (7 affected and 10 asymptomatic) from two of the three families. RESULTS All seven affected patients had abnormally increased CAG repeat numbers (range : 38-59) in SCA7. One asymptomatic 23-year-old woman had 45 CAG repeats in the SCA7. Other 9 asymptomatic family members had 10 CAG repeats in the SCA7. CONCLUSION: We showed that as caucasian patients, Asian patients with ADCA type II also have abnormally increased CAG repeats at SCA7.