Data obtained from patients with PAH show that the severity of PAH is related to an increase in circulating EVs released from stimulated or endothelial cells undergoing apoptosis, probably due to release of soluble vascular cellular adhesion molecule VCAM-1, and that proinflammatory markers, such as monocyte chemoattractant protein MCP-1 and highly specific C-reactive protein, were elevated in PAH patients. This evidence concerns the gene VCAM1 and pulmonary arterial hypertension.