This is strongly supported by previous findings both in knockout mice (for a review, see [3]) and Cav1.3-deficient humans with sinoatrial node dysfunction and deafness (SANDD; OMIM #614896 [24, 25]), in which functional loss of one or both CACNA1D alleles did not lead to a central nervous system (CNS) disease phenotype. This evidence concerns the gene CACNA1D and sinoatrial node dysfunction and deafness.