The present study for the first time, by using the iTRAQ proteomic technology in CHD-PAH patients, has found that (1) a large number of proteins are altered in the plasma of CHD-PAH patients; (2) decreased CPSI expression in CHD-PAH patients may reveal a mechanism that is responsible for decreased endogenous NO that is a critical pathway in the development of PAH; and (3) the decrease of CFHR2 protein, that may possibly activate the complement cascade, in the plasma of CHD-PAH patients may demonstrate the deficiency of the immune system and coagulation mechanism in these patients. The gene discussed is CFHR2; the disease is pulmonary arterial hypertension.