While Usher syndrome is caused by homozygous or compound heterozygous nonsense, frameshift, splice site, and some missense mutations of CDH23, DFNB12 is associated with CDH23 missense hypomorphic alleles with sufficient residual activity to preserve retinal and vestibular function, but not auditory function (Schultz et al. 2011). Here, CDH23 is linked to Usher syndrome.