CACNA2D4 encodes an auxiliary alpha2delta4 subunit of L-type voltage-gated calcium channels that plays a critical role in retinal synaptic transmission. The protein regulates calcium current density and activation/inactivation kinetics of calcium channels, particularly in photoreceptor ribbon synapses 1. CACNA2D4 is essential for proper targeting and expression of Cav1.4 calcium channels to the synaptic membrane in photoreceptors 2. Loss of function mutations cause autosomal recessive cone dystrophy, characterized by slowly progressing cone vision impairment 1. In mouse models, CACNA2D4 deficiency leads to structural abnormalities in ribbon synapses, reduced second-order neuron activity, and impaired cone-mediated responses while maintaining some rod function 3. The gene has also been implicated in broader neurological contexts, including potential roles in microglial phagocytosis regulation in Alzheimer's disease 4 and as a candidate gene in developmental color agnosia 5. Additionally, CACNA2D4 variants have been associated with autism spectrum disorders and bipolar disorder through calcium channel pathway disruptions 67. These findings highlight CACNA2D4's importance in calcium-dependent synaptic transmission and its clinical relevance in retinal and neurological disorders.