A total of 15 patients without pulmonary hypertension (non-PAH), 19 patients with PAH and 25 patients with CTEPH were studied by measuring conventional markers, GTP-related Rap1 levels, RhoA, RalA, Rac1 and Ras in the platelets. The gene discussed is RHOA; the disease is chronic thromboembolic pulmonary hypertension.