Patients with PAH had significantly older age at first diagnosis (36.4 ± 12.9 vs. 32.2 ± 12.0 years old, p < 0.001), lower peripheral oxygen saturation (94.8 ± 5.5 vs. 97.4 ± 3.2%, p < 0.001), lower 6-min walking distance (336.3 ± 99.7 vs. 393.9 ± 82.1 m, p < 0.001), worse WHO functional class (WHO III-IV: 14.2% vs. 5.0%, p < 0.001), higher hemoglobin level (14.1 ± 2.2 vs. 13.5 ± 1.9 g/dL, p = 0.006), higher hematocrit level (42.2 ± 6.5 vs. 40.2 ± 4.9%, p < 0.001) and higher NTproBNP level (median: 774.0 vs. 121.5 pg/mL, p < 0.001). This evidence concerns the gene NPPB and pulmonary arterial hypertension.