CLRN1 (clarin 1) encodes a tetraspanin-family glycoprotein essential for sensory function in hearing and vision. 1 The protein localizes to the plasma membrane and interacts with the cytoskeleton, with specific localization to hair cell synapses in the inner ear and lateral cell contacts between photoreceptors in the retina. 1 In mechanosensory hair cells, Clarin-1 is polarized to the apical cell body and synapses, suggesting a role in ribbon synapse organization. 1 CLRN1 is the causative gene for Usher syndrome type 3A (USH3A), an autosomal recessive ciliopathy characterized by progressive sensorineural hearing loss and retinitis pigmentosa. 2 In affected tissues, CLRN1 mutations disrupt mechanosensory hair bundle integrity in the cochlea and compromise photoreceptor maintenance and periciliary structure in the retina. 2 CLRN1 accounts for a significant proportion of USH3 cases, with ethnic variation in mutation prevalence; approximately 11.4% of Chinese USH cases involve CLRN1 mutations. 3 Mutations include both truncating variants and missense changes, with targeted next-generation sequencing effectively detecting disease-causing variants for molecular diagnosis. 4 Clinical management through early genetic diagnosis enables patient counseling and investigation of emerging therapies including gene and cell-based treatments.