In more detail, HLA-DPB1 is a known COPD gene related to disease severity, SERPINA6 was associated with emphysema, a deletion in ADORA2B was shown to be associated with a decrease in lung fibrosis and pulmonary hypertension, and ELMOD2 is a candidate gene for familial idiopathic pulmonary fibrosis [27, 36, 39, 40]. The gene discussed is ADORA2B; the disease is pulmonary arterial hypertension.