The potential of complement factors as disease progression markers was also shown in a study involving patients with the chronic vascular disease, pulmonary arterial hypertension (PAH) in which the altered levels of factors B and D allowed for their use, in combination with other proteins, in specific algorithms for prediction of disease progression [137] while upregulated expression of C3 protein was shown in a proteomics study on idiopathic PAH sera samples [138]. The gene discussed is C3; the disease is pulmonary arterial hypertension.