rod and cone photoreceptors. The elongated rods are colored yellow and orange, while the shorter cones are colored red. A variety of retinal molecular pathway defects have been matched to multiple known<unk>  gene mutations. Mutations in the rhodopsin gene, which is responsible for the majority of autosomal-dominantly inherited<unk>  cases, disrupts the rod-opsin protein essential for translating light into decipherable electrical signals within the phototransduction cascade of the central nervous system. Defects in the activity of this G-protein-coupled receptor are classified into distinct classes that depend on the specific folding abnormality and the resulting molecular pathway defects. The Class I mutant protein's activity is compromised as specific point mutations in the protein-coding amino acid sequence affect the pigment protein's transportation into the outer segment of the eye, where the phototransduction cascade is localized. Additionally, the misfolding of Class II rhodopsin gene mutations disrupts the protein's conjunction with 11-cis-retinal to induce proper chromophore formation. Additional mutants in this pigment-encoding gene affect protein stability, disrupt mRNA integrity post-translationally, and affect the activation rates of transducin and opsin optical proteins. Additionally, animal models suggest that the retinal pigment epithelium fails to phagocytose the outer rod segment discs that have been shed, leading to an accumulation of outer rod segment debris. In mice that are homozygous recessive for retinal degeneration mutation, rod photoreceptors stop developing and undergo degeneration before cellular maturation completes. A defect in cGMP-phosphodiesterase has also been documented; this leads to toxic levels of cGMP.
Retinitis pigmentosa
Far-sightedness
Photic retinopathy
Chloroquine retinopathy
Corneal dystrophy
Sickle cell retinopathy
Ocular melanosis
Diabetic retinopathy