BMP2 plays a vital role in modulating AV canal morphogenesis, as mice with BMP2 specifically inactivated in AV myocardium showed abnormal AV canal morphology at 9.5 days post coitum (dpc) and pericardial effusion and growth retardation at 10.5 dpc (Ma et al., 2005). This evidence concerns the gene BMP2 and pericardial effusion.