The α2δ subunit regulates many functional aspects of Ca2+ channels, such as gating, regulating voltage dependent kinetics, and increasing functional channel density on the plasma membrane5. There are four proteins that comprise CaVα2δ: CaVα2δ1, CaVα2δ2, CaVα2δ3 and CaVα2δ46. CaVα2δ4 participates in the regulation of membrane expression of CaV channels. It is predominantly expressed in certain types of endocrine cells. It is also detected in the erythroblasts in the fetal liver, in the cells of the zona reticularis of the adrenal gland and in the basophiles of the pituitary7. Defects in CaVα2δ4 are the cause of retinal cone dystrophy 4 (RCD4). RCD4 is characterized by minimal symptoms except for slowly progressive reduction in visual acuity8.
