Susceptibility variants for aHUS in the aHUS-related complement genes were not found in any of the patients in the PPH group (0/25), whereas in 25.0% of patients in the no-PPH group (3/12), a pathogenic complement factor H mutation (CFH) was detected (P = 0.02 vs. PPH group). The gene discussed is CFH; the disease is pulmonary arterial hypertension.