Statistical analysis

All statistical analyses were performed using SPSS 21.0 (IBM Corp.). Quantitative variables were expressed as the mean ± SD and analyzed using Student's t-test. Pearson's χ² test was used to assess the differences between qualitative variables. Statistical analyses of the methylation levels and mRNA expression levels among different genotypes were performed using one-way ANOVA with Bonferroni's correction. The correlation between ALOX5AP mRNA expression level and methylation level was calculated using Pearson's correlation analysis. Unpaired Student's T-test and the Mann-Whitney U test were used for haplotype analysis of CpG loci of the ALOX5AP gene promoter region between ischemic stroke cases and controls. P<0.05 was considered to indicate a statistically significant difference. Study power of sample sizes was evaluated using PASS 15.0 software (NCSS, LLC), with the results showing a power >70%.