Myocardial infarction before and after the age of 45: Possible role of platelet receptor polymorphisms

Influence of Genetic and Epigenetic Factors of P2Y12 Receptor on the Safety and Efficacy of Antiplatelet Drugs

PURPOSE

P2Y12 receptor inhibitors are drugs that decrease the risk of stent thrombosis and lower the long-term risk of non-stent-related myocardial infarction and stroke. They inhibit the binding of adenosine diphosphate (ADP) to the P2Y12 receptor and effectively reduce platelet reactivity. However, considerable variability in the pharmacodynamics response contributes to a failure of antiplatelet therapy; this phenomenon is especially notorious for older drugs, such as clopidogrel. Some genetic polymorphisms associated with these drugs' metabolic pathway, especially in the CYP2C19 gene, can significantly decrease antiplatelet efficacy. There are few reports on the variability stemming from the target of this drug class that is the P2Y12 receptor itself.

RESULTS AND CONCLUSION

This review summarizes the results of research that focus on the influence of P2Y12 genetic polymorphisms on the pharmacodynamics and the efficacy of P2Y12 inhibitors. We found that the conclusions of the studies are unequivocal, and despite several strong candidates, such as G52T (rs6809699) or T744C (rs2046934), they may not be independent predictors of the inadequate response to the drug. Most probably, P2Y12 genetic polymorphisms contribute to the effect exerted by other gene variants (such as CYP2C19*2/*3/*17), drug interactions, or patient habits, such as smoking. Also, epigenetic modifications, such as methylation or miRNA levels, may play a role in the efficacy of antiplatelet treatment.

P2Y12 receptor gene polymorphisms are associated with epilepsy

The basic research indicated that microglial P2Y12 receptors (P2Y12Rs) are involved in the pathophysiology of epilepsy through regulated microglial-neuronal interactions, aberrant neurogenesis, or immature neuronal projections. However, whether the clinic case of epilepsy would be associated with P2Y12 receptor gene polymorphisms is presented with few data. In our study, a total of 176 patients with epilepsy and 50 healthy controls were enrolled. Two single-nucleotide polymorphisms, namely rs1491974 and rs6798347, were selected for analysis. The results revealed that carriers of the G allele of rs1491974 G>A or rs6798347 G>A may be associated with an increased risk of epilepsy (OR = 0.576, 95% CI = 0.368-0.901, p = 0.015; OR = 0.603, 95% CI = 0.367-0.988, p = 0.043). Interestingly, we found that the rs1491974 G>A genotype and allele frequencies have only a significant difference in female instead of male case (p = 0.004 for genotype; p = 0.001 for allele). The subgroup analysis demonstrated that individuals with the rs1491974 G>A genotype might have more frequent seizure (OR = 0.476, 95% CI = 0.255-0.890; p = 0.019). These data implied that both rs1491974 and rs6798347 polymorphisms of P2Y12R would be able to play import roles in epilepsy susceptibility, whereas the rs1491974 polymorphism may be specifically related to seizure frequency.

Study the Association of Nucleotide Polymorphisms in Platelet Receptor and Cytochrome P450 Genes with the Development of Resistance to Antiplatelet Drugs in Patients with Coronary Artery Disease

Aim. To study the association of nucleotide polymorphisms in platelet receptor and cytochrome P450 genes with the development of resistance to antiplatelet drugs in CHD patients.

Material and Methods. The study included 243 patients diagnosed with CHD after coronary artery bypass surgery (CABG), including 140 patients in the acetylsalicylic acid (ASA) treatment group and 103 patients in the dual antiplatelet therapy (DAT) group. All patients were tested for platelet aggregation using an optical aggregometer with inducers: 5 mM ADP and 1 mM arachidonic acid (AA). DNA samples were analyzed by allele-specific PCR for the presence of polymorphisms rs2046934, rs1126643, rs5918, rs6065, rs4244285 in the platelet receptor and cytochrome P450 genes.

Results. No statistically significant differences were found during comparison of the prevalence of the studied polymorphisms in the platelet receptor and cytochrome P450 genes between the groups of aspirin-sensitive and aspirin-resistant patients, as well as between the groups of clopidogrelsensitive and clopidogrel-resistant patients. No association between carriage of the minor and major alleles of the polymorphisms studied and the development of antiplatelet drug resistance was found. In the group of patients on ASA therapy, carriers of the C allele of the T1565C (rs5918) ITGB3 polymorphism had a higher rate of AA-induced platelet aggregation compared to carriers of the T allele (18,49±25,92 vs 10,43±17,34, р=0,004).

Conclusion. Polymorphisms of P2RY12 (rs2046934), ITGA2 (rs1126643), ITGB3 (rs5918), GP1BA (rs6065), CYP2C19*2 (rs4244285) genes are not associated with antiplatelet drug resistance in both patients on ASC therapy and on DAT. The presence of minor alleles of the rs2046934, rs1126643, rs6065, rs4244285 polymorphisms are not associated with increased platelet aggregation activity before CABG.However, in the group of patients on ASA therapy C-allele carriers of the rs5918 polymorphism of the ITGB3 gene had a higher rate of AA-induced platelet aggregation compared to T-allele carriers.

Associations of CYP2C19 and F2R genetic polymorphisms with platelet reactivity in Chinese ischemic stroke patients receiving clopidogrel therapy

OBJECTIVES

Genetic variation has been considered a major contributor to the high variability in the response to dual antiplatelet therapy in patients with acute ischemic stroke or transient ischemic attack. Recently, incidences of ischemic stroke are increasing rapidly in China. We aimed to evaluate the influence of potential determinants on the response of antiplatelet therapy and adverse events in Chinese ischemic stroke patients receiving clopidogrel-aspirin treatment.

METHODS

Based on the clopidogrel drug response pathway and the coagulation and anticoagulation function, we systematically selected 34 genetic polymorphisms in 12 candidate genes. Three hundred and eight patients were divided into 2 groups according to their degree of inhibition of platelet aggregation. Multivariate analysis was then performed to assess the influence of demographic, clinical and genetic factors on platelet reactivity in Chinese ischemic stroke patients.

RESULTS

We found that polymorphisms in CYP2C19 and F2R genes were still significantly associated with platelet reactivity in Chinese ischemic stroke patients (P = 0.037 and 0.015). The newly identified rs168753 in F2R gene may influence the efficacy to clopidogrel-aspirin therapy for ischemic stroke patients. We also found that ischemic stroke patients with low level of inhibition of platelet aggregation had higher risk of recurrent ischemic events (P = 0.001).

CONCLUSIONS

Together, these results emphasized the necessity of genotype-directed antiplatelet therapy and facilitated to minimize adverse ischemic events.

Single-nucleotide polymorphisms of the SLC17A9 and P2RY12 genes are significantly associated with phantom tooth pain

Phantom tooth pain (PTP) is a rare and specific neuropathic pain that occurs after pulpectomy and tooth extraction, but its cause is not understood. We hypothesized that there is a genetic contribution to PTP. We focused on solute carrier family 17 member 9 (SLC17A9)/vesicular nucleotide transporter (VNUT) and purinergic receptor P2Y12 (P2RY12), both of which have been associated with neuropathic pain and pain transduction signaling in the trigeminal ganglion in rodents. We sought to corroborate these associations in humans. We investigated gene polymorphisms that contribute to PTP. We statistically examined the association between genetic polymorphisms and PTP vulnerability in 150 patients with orofacial pain, including PTP, and 500 healthy subjects. We found that the rs735055 polymorphism of the SLC17A9 gene and rs3732759 polymorphism of the P2RY12 gene were associated with the development of PTP. Carriers of the minor allele of rs735055 and individuals who were homozygous for the major allele of rs3732759 had a higher rate of PTP. Carriers of the minor allele of rs735055 reportedly had high SLC17A9 mRNA expression in the spinal cord, which may increase the storage and release of adenosine triphosphate. Individuals who were homozygous for the major allele of rs3732759 may have higher P2RY12 expression that is more active in microglia. Therefore, these carriers may be more susceptible to PTP. These results suggest that specific genetic polymorphisms of the SLC17A9 and P2RY12 genes are involved in PTP. This is the first report on genes that are associated with PTP in humans.

A preliminary identification of PIN1 SNP linkage in patients with coronary heart disease from Handan, China

Our aim was to perform an initial assessment of the polymorphic patterns of the PIN1 gene in patients with coronary heart disease (CHD). The PIN1-encoded protein (Pin1) suppresses eNOS-NO signaling and may impair cardiovascular function. Blood collection, DNA extraction, PCR amplification and gene sequencing were performed for thirty CHD participants living in central China, focusing on nine single nucleotide polymorphisms (SNPs). Their genetic linkages were revealed and their allele frequencies were compared with SNP data from the NCBI. Three major linkage patterns were identified: [1.rs2287839-5.rs2233682], [3.rs2233679-4.rs1077220-8.rs2287838] and [6.rs889162-7.rs2010457], suggesting correlated involvement in CHD and possible simultaneous genetic origin in ancient times. The frequencies of six SNPs are consistent with the NCBI data, while the frequencies of three SNPs (2.rs2233678, 4.rs1077220 and 9.rs4804461) are not consistent with the NCBI. Especially, the 3.rs2233679-4.rs1077220 linkage is different from other populations worldwide and may be an interesting genetic characteristic of Chinese CHD patients. Predictably, 1.rs2287839, 2.rs2233678, 3.rs2233679 and 5.rs2233682 may be strongly associated with CHD risk, although this requires future verification. The PIN1 SNP linkages lay a new genetic foundation for discovering novel molecular mechanisms of CHD and for exploring PIN1-based targeted treatment of CHD with nitric oxide regulatory therapies in clinical practice.