Increased levels of pro-inflammatory serum cytokines (e.g., interferon-gamma; interleukin (IL)-1beta, -2, -4, -5, -6, -8, -10, -12p70, and -13; tumor necrosis factor-alpha (TNF–α)) were demonstrated in patients with IPAH and HPAH compared to the control group. The gene discussed is TNF; the disease is idiopathic pulmonary arterial hypertension.