Most cases of macular degeneration are isolated, individual, occurrences, mostly in people over age 60. Much more rarely, younger people, including infants and young children, develop macular degeneration, and they do so in clusters within families, because their disorders are inherited, caused by mutated genes.
Symptoms typically develop in childhood or teen years.
However a variant of Stargardt's disease, called fundus flavimaculatus , has the same symptoms, but they do not become manifest until early adulthood. Symptoms include decline in visual acuity, drusen spots on the macula and scarring of the macula. Stargardt's disease has an autosomal recessive pattern of inheritance. The spent retinol is a result of the light-sensing photoreaction in the discs. The transport protein is located at the rim of the discs, so was named rim protein.