When trying to explore the genotype-phenotype correlation, we found that PAH patients with BMPR2 causal and rare mutations were younger at diagnosis (27.2y vs. 31.6y, p = 0.0003) and had more severe pulmonary hemodynamic impairment and a worse cardiac index (2.6 L/min/m2 vs. 3.0 L/min/m2, p = 0.0017) (Table 5) compared with those without BMPR2 mutations, in accord with previous reports [9]. The gene discussed is BMPR2; the disease is pulmonary arterial hypertension.