Usher syndrome is the most common cause of deaf-blindness. Mutations in the protocadherin-15 (PCDH15) gene cause Usher syndrome type 1 F (USH1F), which makes up about 3-11% of all Usher syndrome cases. As a component of tip links of the inner ear hair cells, PCDH15 binds to cadherin-23 (CDH23) to convey force from sound stimuli to the mechanosensory transduction channels.