Association of glutathione S-transferase omega polymorphism and spinocerebellar ataxia type 2

Abstract Background Spinocerebellar ataxia type 2 is a neurodegenerative disorder caused by a CAG repeat expansion in ATXN2 gene. There is high clinical variability among affected patients suggesting the occurring of modifier genes influencing the clinical phenotype. Objective The objective is to assess the association of GSTO1 rs4925 and GSTO2 rs2297235 SNPs on the clinical phenotype in SCA2 patients. Methods A case-control study was performed in a sample of 120 SCA2 Cuban patients and 100 healthy subjects. Age at onset, 60° Maximal Saccade Velocity and SARA score were used as clinical markers. GSTO1 rs4925 and GSTO2 rs2297235 SNPs were determined by PCR/RFLP. Results Distribution of the GSTO1 alleles and genotypes was nearly equal between the control group and SCA2 patients. GSTO1 genotypes were not associated to clinical markers in SCA2 patients. Distribution of the GSTO2 “G” allele and “AG” genotype differed significantly between SCA2 patients and controls. Symptomatic SCA2 individuals had a 2.29-fold higher chance of carrying at least one “G” allele at GSTO2 rs2297235 than controls (OR = 2.29, 95% CI: 1.29–4.04). GSTO2 genotypes were significantly associated to age at onset (p = 0.037) but not to 60° Maximal Saccade Velocity or SARA score in SCA2 patients. Conclusion The GSTO1 rs4925 polymorphism is not associated to SCA2. Meanwhile, the GSTO2 rs2297235 “AG” genotype is associated to SCA2 but failed to show any association with clinical markers, with the exception of a potential association with the age at disease onset.