Cone Opsins and Inherited Retinal Disease

Opsins are the light receptors in retinal rod and cone photoreceptor cells that initiate vision in response to a light stimulus. Rhodopsin is the opsin in rods, and the influence of mutations that disrupt its structure and function has been characterized in detail. Less is known about cone opsins, the opsins in cones, and their gene arrays. Cones are responsible for color vision and high visual acuity and operate under most lighting conditions. There are up to three types of cone opsins (L-, M-, and S-opsin) in most vertebrates, each defined by their distinct spectral sensitivities. Disruptions in the cone opsin gene array cause a variety of inherited retinal disorders, including blue cone monochromacy, Bornholm eye disease, and tritan color vision deficiency. In this review, we discuss what is known about cone opsin mutations and the inherited cone dysfunctions that they cause. We also present the available mouse models that are being used to better understand the pathophysiology promoted by cone opsin defects.