Study On The Association Of Functional Single Nucleotide Polymorphisms In P2Y12 Gene With Coronary Heart Disease And Clopidogrel Therapy Effect

Coronary heart disease (CHD) is a multifactorial disease. Numerous factors including genetic and environmental ones are risky factors for CHD. Atherosclerosis (As) is the key factor in CHD, but the mechanism is still unknow. The activation of platelet and abnormal coagulation response plays an important role in the formation of As, and has the positive relationship with the development and progress of CHD.Platelet membrane receptor P2Y12 gene encodes a kind of important G_αi coupled receptor. This receptor has a crucial role in many functions of platelet. On the one hand, activated P2Y12 receptor causes the action of platelet itself, on the other hand, it causes the decrease of intracellular cAMP level via restricting adenylyl cyclase by actived Gi signal transmit pathway. Meanwhile, activated P2Y12 receptor stimulates PI3K, Akt, Rap 1b and potassium channels, and causes the occurrence of downstream events of P2Y12 receptor signal transmit pathway, including release and activation ofα-granule, programmed express of platelet GMP140, activation of fibrinogen-receptor complex, ADP-mediated generation of thromboxane A₂, agonist-induced dense granule release and procoagulant activity. It also Fuels the inflammatory responses through the exposure of P-selectin on the platelet surface. Thus, P2Y12 receptor plays a central role in platelet activation. Besides, p2y12 gene knockout mice model experiment proved P2Y12 receptor is the target site of clopidogrel. Until recently, reports from abroad indicated that certain single nucleotide polymorphisms (SNPs) ofP2Y12 gene may influence the sensibility of CHD in individuals with different genotype via diverse activation level of platelet by influencing the activation or quantity of products expressed by P2Y12 gene. Data from clinic indicate that there exists vast variation of medical efficiency in patients with thrombus after antiplatelet treatment with usage of clopidogrel. They speculated that the genetic background of patients maybe associated with medical efficiency, and there already have manypositive results.In the present study, possible association of 2 functional SNPs (C34T, G52T) in P2Y12 gene and CHD or levels of platelet action, procoagulant pathway activation were carried out in a Chinese population including 177 CHD patients and 61 controls using created restriction site-polymerase chain reaction/restriction fragment length polymorphism (CRS-PCR-RFLP). Meanwhile, possible association of those SNPs (C34T, G52T) above and medical efficiency of antiplatelet drug clopidogrel were carried out in a Chinese population including 73 stable angina pectoris (SAP) patients using CRS-PCR-RFLP. The results are as follows:1. The frequency of T allele in CHD patients was significantly higher than those in controls. When the patients were divided into acute coronary syndrome (ACS) and stable angina pectoris (SAP), the frequency of T allele for ACS patients was higher than controls, but no significant differences between ASC patients and SAP patients. While the frequency of T allele for SAP patients was higher than those in controls.2. The distributions of G52T allelic and genotype frequencies did not significantly differ between patients and controls.3. Compared with controls, levels of Maximum platelet aggregation ratio (MAR) , granule membrane protein (GMP140) , Fibrinogen (FIB) were significantly higher, and level of prothrombin time (PT) was significantly lower in CHD patients. After subgrouped in CHD patients, levels of MAR,GMP140, FIB were gradually higher in ACS patients, SAP patients and controls. Compared with controls, level of PT was significantly lower in ASC patients. The differences all have statistical meaning.4. Multi-logistic regression model suggested that plasma GMP140 level was significantly associated with CHD.5. After subgrouped SAP patients according to P2Y12 genotype, before single medicine treatment with SAP patients by clopidogrel, level of MAR had no significant differences between carriers of mutation allele and carries of wild type genotype for sites 34 and 52. After 24 hours of single medicine treatment with SAP patients by clopidogrel, level of MAR and reduced level of MAR had significant difference between carriers of mutation allele(TT, TC) and carries of wild type genotype (CC) for site 34.