ABCG1 and ischemic stroke: In order to give a deeper explanation of the role of DNA methylation on ischemic stroke and atherosclerosis based on the function of DNA methylation affecting gene expression, the mRNA expression levels should be examined to investigate the correlation between mRNA levels and methylation for each gene, but unfortunately, we were unable to detect mRNA levels for APOE and ABCG1 in our subjects since the blood samples have been stored for too long time.