Conversely, the measured RAGE ligands: serum S100A9 and HMGB1 in patients with iPAH did not differ from controls (S100A9 [μg/ml] 1.4±0.6 vs. 0.9±0.1, p = 0.374; and HMGB1 [pg/ml] 1419.4±610.1 vs. 415.1±65.5, p = 0.067; fig. This evidence concerns the gene S100A9 and idiopathic pulmonary arterial hypertension.