NT-proBNP (normal range: less than 150 pg/ml) was not available in two IPAH patients, one CTEPH patient and six healthy controls and turned out to be increased in both IPAH and CTEPH as compared to control (IPAH vs CTRL vs CTEPH: median = 997.5 pg/ml (IQR: 186–2092) vs 84 pg/ml (IQR: 42–227) vs 1,120 pg/ml (IQR: 320–2,333); IPAH vs CTRL p < 0.0001, CTEPH vs CTRL p < 0.0001, Figure 1D), with no significant differences between CTEPH and IPAH. This evidence concerns the gene NPPB and chronic thromboembolic pulmonary hypertension.