The Relationship Between Middle Cerebral Artery Stenosis And Angiotensin-converting Enzyme Gene Polymorphism

Middle cerebral artery is the major intracranial branch of internal carotid artery.Two-thirds blood supply of the cerebral hemispheres depends on it. The frequency of MCA stenosis is highest in intracranial arteries. In Asia, MCA stenosis is the most commonly identified intracranial vascular lesion. Large number of epidemiological studies and animal experiments show that the majority of ischemic cerebrovascular disease are under the control of genetic factors, which is polygenic inheritance disease. Angiotensin-converting enzyme (ACE) gene is the candidate genes ,and there are many reseaches and reports on it . The ACE gene is located on the long arm of chromosome 17 (17q23),most studies focused on an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene as a marker for a functional polymorphism. Association studies between the ACE gene insertion/deletion (I/D) polymorphism and ischemic cerebrovascular diseases are continued, mostly with conflicting results. At present,numerous studies have reported a relation between the D allele and cardiovascular diseases, but findings have been controversial. Similarly, there are still controversy in relationship between ACE polymorphism and MCA stenosis.The aim of this study is to explore the relationship between MCA stenosis and the polymorphism of the ACE gene.Diagnosis of MCA stenosis was based on results of transcranial Doppler ultrasound examination. 148 patients with MCA stenosis were investigated and compared with 62 volunteers as a control group.Alleles of an insertion/deletion polymorphism of ACE gene were detemined by polymerase chain reaction and the associations between MCA stenosis and the ACE polymorphism were evaluated by chi-squared test and logistic regression.There was no significant difference in gender, age between the case group and the control group in this experiment, but there were significant differences in the history of hypertension, the grade of hypertension, a history of diabetes and smoking history.The distribution of ACE genotypes in the case group were as follows: II, 47 (31.8%); ID, 61 (41.2%); and DD, 40 (27%), which was not significantly different from the distribution in the control group: II, 24 (38.7%); ID, 28 (45.2%); and DD, 10 (16.1%) ( 2=2.81, 2 df, P=0.2443). In this experiment statistics, we also found that the association between MCA stenosis and carotid artery intima-media thickness. Increased carotid IMT is a marker of generalized atherosclerosis and is associated with future myocardial infarction and stroke.Usually 1.1 mm≤IMT<1.5 mm was judged as increased carotid IMT, IMT≥1.5mm was judged plaque formation., A significant positive association was present between the increased carotid IMT and MCA stenosis (P <0.001). The results of the logistic regression analysis of the multiple factors in MCA stensis show that hyperten- sion history, hypertension grade, smoking history, as well as increased carotid IMT are the independent risk factors of MCA stenosisIn sum, we have reached a conclusion:1. The polymorphism of ACE gene is not associated with MCA stenosis2. Hypertension history and the grade of hypertension are associated with MCA stenosis , furthermore hypertension grade is an independent risk factor of MCA stenosis; 3. Increased carotid IMT is an independent risk factor for the occurrence of MCA stenosis;4. A significant positive association was present between the smoking history and MCA stenosis,it is also an independent risk factor.