In summary, at diagnosis we found significantly increased plasma levels of IL-10, TGFβ, and CXCL9 in IPAH patients, of IL-6, CXCL9 and CXCL13 in CTD-PAH patients, and of CXCL9 in CTEPH patients. This evidence concerns the gene CXCL9 and idiopathic pulmonary arterial hypertension.