PTGIS and ischemic stroke: Several studies have shown that single nucleotide polymorphisms (SNPs) in the prostaglandin H synthase-1 gene (PTGS1), PTGS2, thromboxane synthase-1 gene (TXAS1), prostacyclin synthase gene (PTGIS) and thromboxane A2 receptor gene (TXA2R) are associated with cardiovascular disease or ischemic stroke [14–22].