PCDH15 and hereditary disease: The importance of cilia in the broader context of genetic disorders affecting vision and hearing is evident by the involvement of numerous Usher-associated genes (i.e. MYO7A, USH2A, USH1C, USH1G, PCDH15, CDH23), including those proposed for atypical forms (i.e. CEP250) or deafness-blindness syndromes (e.g. CEP78), in ciliary function.