USH2A and retinitis pigmentosa: For example, although the proportion of cochlear hair cell Ush2a C230072F16Rik did not diminish with ARHL, mutations in its marker gene USH2A causes Usher syndrome type IIa, an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and retinitis pigmentosa (Eudy et al., 1998).