Previous reports revealed a higher expression of exon 8b in the sinoatrial node and cochlear hairs cells, which explains why a Cav1.3 loss-of-function mutation in exon 8b results in bradycardia and congenital deafness (SANDD; OMIM #614,896 [10,48]). This evidence concerns the gene CACNA1D and sinoatrial node dysfunction and deafness.