A statistically significant increase in circulating endothelial microparticles (CD31+CD42b−) was identified in patients with IPAH compared to healthy controls (330±32 events/μl PPP vs. 185±27 events/μl PPP), as shown by the pairing of bars to the right in Figure 2. This evidence concerns the gene PECAM1 and idiopathic pulmonary arterial hypertension.