CACNA1D and deafness: It is well established that mutations in key synaptic proteins, including CaV1.3 Ca2+ channels and otoferlin, cause deafness but only minor balance defects at worst (Platzer et al., 2000; Brandt et al., 2003; Dou et al., 2004; Roux et al., 2006; Dulon et al., 2009).