This gene encodes the inhibitory (or gamma) subunit of the cone-specific cGMP phosphodiesterase, which is a tetramer composed of two catalytic chains (alpha and beta), and two inhibitory chains (gamma). It is specifically expressed in the retina, and is involved in the transmission and amplification of the visual signal. Mutations in this gene are associated with retinal cone dystrophy type 3A (RCD3A). [provided by RefSeq, Mar 2010].