Analysis of EGFR serum concentrations showed that CTEPH patients (38.52 ± 15.81 ng/mL) and iPAH patients (38.6 ± 9.7 ng/mL) displayed lower values when compared to healthy volunteers (CTEPH controls 47.1 ± 11.6 ng/mL, p = 0.021; iPAH controls 49.1 ± 11.4 ng/mL, p = 0.001) (Figure 4A,B). This evidence concerns the gene EGFR and idiopathic pulmonary arterial hypertension.