In multivariate analysis, the RDW was independently associated with the presence of pulmonary hypertension (OR = 1.521, 95% CI 1.001 to 2.313, p < 0.05) after adjusting for brain natriuretic peptide (BNP), white blood cell count, sex, haemoglobin, and pulmonary artery-to-ascending aorta ratio. The gene discussed is NPPB; the disease is pulmonary arterial hypertension.