CDH23 (cadherin related 23) is a calcium-dependent cell adhesion protein essential for hearing and balance. Functionally, CDH23 is required for establishing and maintaining proper stereocilia bundle organization in cochlear and vestibular hair cells during late embryonic and early postnatal development 1. It operates within the USH1 protein interactome alongside USH1C, USH1G, and MYO7A to mediate mechanotransduction in cochlear hair cells 2. CDH23 mutations cause a broad phenotypic spectrum of sensorineural hearing loss, ranging from non-syndromic autosomal recessive deafness (DFNB12) to syndromic Usher syndrome type 1D (USH1D), characterized by congenital to progressive, age-related hearing impairment 3. Clinically, CDH23 ranks among the most important deafness genes in East Asian populations, with detection rates exceeding 10 cases in large patient cohorts 4. In USH1, MYO7A is the predominant causative gene (60% of cases), while CDH23 mutations contribute significantly to the disease burden 5. Genotype-phenotype correlations show that specific variant combinations predict disease severity and age of onset, with residual CDH23 function determining clinical presentation 3. These findings establish CDH23 as a critical gene for inner ear development and function, with mutations causing approximately 10-15% of genetic hearing loss cases in diverse populations.