PCDH15 and Usher syndrome: Mutations of PCDH15 also cause similar disorders, including autosomal recessive deafness 23 (OMIM: 609533) and Usher syndrome type 1D (OMIM: 601067) or Usher syndrome type 1F (OMIM: 602083) (Ahmed et al., 2003; Doucette et al., 2009).