PRG4 and atrial septal defect: Conversely, post-CPB ASD samples were characterized by the specific downregulation of several genes, the most relevant of which were those involved in the regulation of the complement system (C4a,/C4b, CFI, CFB) and inflammation (VEGFR, SLP1), cell adhesion (PRG4, MSLN), and oxidative stress (PTGIS and AOX1) (Table 5).