HP and Patent ductus arteriosus: Moreover, several identified antigens have been previously correlated to PDA, although not in association with immunoglobulins, namely TTR (thyroid hormone-binding protein) and S100A9 (protein S100-A9) were found in IgG CIC [25,26], ADIPOQ (adiponectin), CDH5 (cadherin-5), FCGBP (IgGFc-binding protein), HP (haptoglobin), GAPDH (glyceraldehyde-3-phosphate dehydrogenase), and SERPINA1 (serine proteinase inhibitor A1) in IgM CIC [24,27,28,29], BRSK2 (BR Serine/Threonine-Protein Kinase 2) in IgA CIC.