Harmonin protein is a scaffold protein encoded by the USH1C gene located on 11p15.1chromosome.  This protein contains PDZ domains, a coiled-coil region with a bipartite nuclear localization signal and a PEST degradation sequence.It has the ability to bind to many other proteins in cell membranes and coordinates their activities.  Harmonin plays a role in the development and maintenance ofstereociliaprojections that line in the inner ear and bend in response to sound waves.  Expressed in the photoreceptors, the function of the harmonin-protein complex in the retina is not well known, but it is thought to be important in the development and function of photoreceptor cells. 

Defects in the harmonin protein are the cause of Usher syndrome 1C and Deafness, autosomal recessive, 18A.  Usher syndrome type 1 is characterized by profound congenital sensorineural deafness, absent vestibular function and prepubertal onset of progressive retinitis pigmentosa leading to blindness.  Deafness, autosomal recessive, 18A is a form of non-syndromic sensorineural hearing loss.