MYO3A encodes an unconventional myosin motor protein with dual actin-dependent motor and protein kinase activities that is essential for auditory function 1. The protein localizes to stereocilia tips in cochlear and vestibular hair cells, where it plays a critical role in hair bundle development and morphogenesis 2. MYO3A influences stereocilia number, length, and spacing, contributing to the characteristic staircase architecture of auditory hair bundles 3. Mechanistically, the protein transports actin regulatory factors to actin filament plus ends and generates or stabilizes short actin filaments that are intermediates for stereocilia widening 3. MYO3A also interacts with protocadherin 15 (PCDH15), a core component of the mechanotransduction complex at stereocilia tips 4. Pathogenic variants in MYO3A cause both autosomal recessive (DFNB30) and autosomal dominant (DFNA90) non-syndromic hearing loss 12. The hearing loss phenotype is typically progressive, with onset ranging from birth to the second decade of life, eventually progressing to severe-to-profound deafness 2. Mutant proteins show altered ATPase activity and motility defects 4. Early identification of MYO3A variants enables timely clinical intervention for progressive hearing loss 2.