As a heritable regulation , epigenetics can regulate gene expression by other ways without changing the DNA sequence ,and change cell or individual phenotypes .DNA methylation is an issue in the field of epigenetics research.Recently,many studies have been demonstrated that the methylation of repetitive DNA ,spe-cific gene and CpG island and loss of imprinting play an important role in tumor occurrence .As the development of technological approaches to DNA methylation ,we have a more comprehensive understanding on methylation pat-terns.As specific markers,abnormal methylation sites in the genome can be used in the diagnosis ,treatment and prognosis predictor of disease .For tumor development caused by DNA methylation ,the application of demethylat-ing drugs have achieved good effect in clinical treatment .

Objective:To investigate the risk factors of infarct growth rate of elderly acute ischemic stroke(AIS)patients with endovascular treatment(EVT)and its influence on prognosis.Methods:Elderly AIS patients who underwent EVT at Beijing hospital from June 2016 to October 2020 were retrospectively included.Infarct growth rate(ml/h)=infarct core volume(ml)/time from stroke onset to CTP examination(h).Based on the rate of infarct growth and the patient's clinical severity, ROC curve was established, and the cut-off value of the ROC curve was obtained.By the cut-off value of the rate of infarct growth, the patients were divided into cerebral infarct slow-growth group and rapid-growth group.Predictors of rapid growth in infarct were analyzed by univariate and multivariate analysis.The patients were divided into good prognosis group(mRS score 0-2)and poor prognosis group(mRS score 3-6)according to the mRS score at the day 90 and the predictors of poor prognosis were analyzed separately.Results:A total of 67 elderly AIS patients were included with age ranging from 65-96 years and an average of(78.8±7.6)years.(1)The cut-off value of the optimal infarct growth rate for patients with good and poor prognosis was 8.89 ml/h.The patients were divided into fast-growth group(26 patients)and slow-growth group(41 patients)according the cut-off value.(2)Multivariate logistic regression showed that only poor collateral circulation was an independent predictor for fast infarct growth( OR=0.162, 95% CI: 0.053-0.489).(3)Faster infarct growth rate( OR=1.173, 95% CI: 1.044-1.318)and high NIHSS score( OR=1.146, 95% CI: 1.018-1.291)were predictors of poor prognosis. Conclusions:Collateral circulation status is a major influencing factor for the infarct growth rate, and a faster infarct growth rate is a predictor of poor prognosis for elderly AIS patients after endovascular treatment.