Higher levels of ET-1 predicted increased values of mPAP (28% per 0.1 pg/ml increase in ET-1, p = 0.06, Table 4A) and higher risk of PAH (PR = 2.35 per 0.1 pg/ml increase in ET-1, p = 0.033, Table 4B) in the univariable analysis. This evidence concerns the gene EDN1 and pulmonary arterial hypertension.