Genetic deletion of Cav1.3 in mice (Cav1.3−/−) causes congenital deafness, sinus bradycardia, and various degrees of atrioventricular (AV) block consistent with region-specific expression (Mangoni et al., 2003; Hu et al., 2004; Qu et al., 2005a). This evidence concerns the gene CACNA1D and Sinus bradycardia.