These proteins (pulmonary surfactant protein B (SP-B), osteopontin, kallikrein-5 and galectin-3) were selected primarily on the basis of potential mechanistic and clinical relevance to the lung or pulmonary hypertension (SP-B, osteopontin, kallikrein-5) and availability of high-quality ELISA assays, yet a paucity of information regarding their role in CDH. The gene discussed is KLK5; the disease is pulmonary arterial hypertension.