PRPH2 and retinal degeneration: Elevated cGMP levels are implicated in inherited retinal degenerations arising from mutations in genes not only involved directly in its metabolism [e.g., PDE6B, aryl‐hydrocarbon‐interacting protein‐like 1 (AIPL1), CNGA1, CNG channel subunit beta 1 (CNGB1), guanylate cyclase 2D (GUCY2D), and guanylate cyclase 1 soluble subunit alpha 1 (GUCY1A)] but also those involved in supporting photoreceptor integrity and phototransduction processes such as RHO, RPE65, and peripherin 2 (PRPH2).