WNT1 and atrial fibrillation: Quantitative measurement showed that the normalized average area between the frontal bones (total area of AF/length of PFS from jugum limitans to bregma) was significantly larger in Wnt1-Cre;Fgfr2−/− at P3 (P=0.0167, n=7) and P5 (P=0.0003, n=9) compared to littermate controls (Fig. 1H).