MEGF8 and Pulmonic stenosis: In addition to the inversion of heart looping observed in some Megf8−/− and Megf8L1775P/L1775P embryos, loss of Megf8 function leads to a complete, or nearly complete, absence of the mitral and tricuspid valves, swollen atria, transposition of the outflow tract, pulmonary stenosis, and atrial and ventricular septal defects (Figure 3—figure supplement 3).