Significant association between DHFR promoter methylation and ischemic stroke in a Chinese hypertensive population

OBJECTIVE: DHFR encodes dihydrofolate reductase, a major enzyme in the metabolism of folate, and is a candidate gene for ischemic stroke (IS). Therefore, we aimed to investigate the association between DHFR promoter methylation and IS in a Chinese population with primary hypertension. METHODS: Quantitative methylation‐specific PCR was used to measure the level of DHFR promoter methylation. A multivariate logistic regression model was used to investigate the association between DHFR promoter methylation and IS. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic value of DHFR promoter methylation for IS. RESULTS: The level of methylation of the DHFR promoter in the IS group was significantly lower than that in the hypertensive group (median [interquartile range]: 9.11 [2.81‐16.20] vs 24.94 [7.16‐56.45], P < .001). DHFR promoter methylation and homocysteine (Hcy) levels were both related to IS, with an ORs (95% CI) of 0.976 (0.967‐0.984) and 1.057 (1.027‐1.108), respectively. The areas under the curve for the diagnosis of DHFR promoter hypomethylation in IS were 0.603 (95% CI, 0.527‐0.678) in men and 0.754 (95% CI, 0.693‐0.815) in women. A dual‐luciferase reporter assay revealed that the target sequence in the DHFR promoter upregulated gene expression. CONCLUSION: There is a significant association between methylation of the DHFR promoter and IS in this Chinese hypertensive population. Hypomethylation of the DHFR promoter may serve as a novel marker for the diagnosis of IS in women.