Cone cGMP-specific 3',5'-cyclic phosphodiesterase subunit alpha' is an enzyme that in humans is encoded by the PDE6C gene. This gene encodes the alpha-prime subunit of cone phosphodiesterase, which is composed of a homodimer of two alpha-prime subunits and 3 smaller proteins of 11, 13, and 15 kDa. Mutations in this gene are associated with cone dystrophy type 4 (COD4).