ABCC6 and atrial fibrillation: Analysis revealed presence of AF calcification in one 16–18M Abcc6−/− mouse (Supplementary Figure S2A), however, there was no overall apparent elevation in calcium staining or the presence of calcified nodules in Abcc6−/− discs (Figure 3J), suggesting that discs are not susceptible to pathological mineralization following the loss of ABCC6.