BMPR2 and idiopathic pulmonary arterial hypertension: BMPR2 (Figure 2(d)) was higher in IPAH group than COPD-PH group (22.35 ± 15.60 versus 2.57 ± 0.99 pg/mL, p = 0.019), but there is no significant difference between COPD-PH and non-PAH group (2.57 ± 0.99 versus 6.41 ± 3.27 pg/mL, p > 0.5).