LINE-1 methylation is associated with an increased risk of ischemic stroke in men

The level of global DNA methylation may be related to the cerebrovascular disease. The methylation level of Long Interspersed Nucleotide Element 1 (LINE-1) can represent the global methylation level. We investigated the association between the methylation levels of LINE-1 and ischemic stroke in Chinese. Two hundred and eighty patients of ischemic stroke and 280 age- and sex-matched controls were enrolled. The mean percentage of three CpG sites of LINE-1 was calculated for each subject and was used for analysis. Twenty four samples were re-checked for reproducibility of the methylation assay. Multivariate regression model was used to estimate the odds ratio of stroke risk for one percent change of methylation. Sex-specific analysis was also conducted. Thirty-two cases and 11 controls did not pass the methylation assay criteria, and were excluded from further analysis. The intra-class correlation has a coefficient of 0.97 for the methylation assay. The stroke cases had a lower methylation level than controls (p=0.002), especially male subjects (p=0.001). Sex-specific analysis showed that a decrease of 1% methylation level in men could increase a stroke risk by 1.2-fold after adjusting for other risk factors. LINE-1 methylation levels did not have a significant association with stroke in women. The present study shows that a lower level of LINE-1 methylation was associated with a higher risk for ischemic stroke in men, but methylation level in women did not affect the stroke risk. Our finding in Chinese is consistent with a previous result based on elderly white men.