CNGB3 encodes the beta subunit of the cone cyclic nucleotide-gated (CNG) channel, a pore-forming component essential for cone photoreception. In darkness, elevated intracellular cGMP levels keep the channel open, allowing inward Na+ and Ca2+ currents that depolarize the membrane and enable neurotransmitter release [UniProt]. Upon light absorption, cGMP levels decline, closing the channel and hyperpolarizing the membrane, thereby signaling light detection as the endpoint of the phototransduction cascade [UniProt]. CNGB3 mutations cause autosomal recessive achromatopsia (ACHM), a cone dysfunction syndrome affecting approximately 1 in 30,000 people 1. Up to 90% of achromatopsia patients carry mutations in CNGA3 or CNGB3 21. The condition manifests at birth or early infancy with poor visual acuity, nystagmus, photophobia, and complete color vision loss due to functional loss and progressive cone photoreceptor degeneration 21. CNGB3 mutations also associate with Stargardt disease 1, though the primary focus for gene therapy development targets CNGB3-linked achromatopsia 3. Currently, no FDA-approved treatment exists, but multiple gene therapy clinical trials at the phase I/II stage are underway for CNGB3-associated achromatopsia, with preclinical studies demonstrating anatomical and functional improvements in animal models 214.