CDH23 and deafness: So far, there is an increasing number of multiple mutant alleles in a wide variety of genes due to spontaneous or chemically induced mutations allowing not only the discovery of deafness genes mutation but also the molecular mechanisms of hearing and the pathogenesis of deafness as for the protein tyrosine phosphatase receptor type Q gene (PTPRQ; MIM 603317) (Goodyear et al. 2003) and lipoxygenase homology domains 1 gene (LOXHD1; MIM 613072) (Grillet et al. 2009), and cadherin-23 gene (CDH23; MIM 605516) (Schwander et al. 2007; Manji et al. 2011).