Plasma GDF15 concentrations in patients with PVOD, idiopathic PAH (IPAH), heritable PAH (HPAH), group 2–4 PH (Other PH), and chronic obstructive pulmonary disease without PH (COPD) as well as individuals acting as healthy controls were quantified (Figure 1A). The gene discussed is GDF15; the disease is pulmonary venoocclusive disease.