Analysis of ATXN2 trinucleotide repeats in Korean patients with amyotrophic lateral sclerosis

ATXN2 intermediate-length trinucleotide repeat expansions have been reported as a risk factor for amyotrophic lateral sclerosis (ALS) in various ethnicities. We tried to confirm this finding in Korean patients with ALS by screening ATXN2 cytosine-adenine-guanine nucleotide sequences (CAG) repeat lengths in 464 unrelated ALS patients and 703 controls. The most common and the highest CAG repeat lengths in the controls were 22 and 28, respectively, whereas those in ALS patients were 22 and 33, respectively. The frequency of CAG repeat lengths of 30 or more was significantly different between the 2 groups after Bonferroni correction (1.5% in ALS vs. 0% in controls, corrected p = 0.0075). There were no significant differences in gender, age at onset, site of onset, functional rating scale-revised score at initial visit, calculated progression rate, or survival between patients with CAG repeat lengths of 30-33 and patients with CAG repeat lengths <30. These findings support the notion that intermediate-length ATXN2 repeat expansions might be a risk factor in Korean patients with ALS.