Leber's Congenital Amaurosis
A possible mechanism for Leber's congenital amaurosis has been proposed as the deficiency of RPE65. If one was lacking in RPE65 the RPE would be unable to store retinyl esters, and thus the bleach and recycle pathway would be compromised. This would lead predominantly to night blindness (as the rods have only one mechanism, via the RPE, to regenerate their chromophore) in the early stages of the disease, at which stage the cone photoreceptors would be spared, as they have the alternate Muller cell pathway for photopigment regeneration.
In the later stages of the disease, general retinopathy is observed as the rod photoreceptors lose their ability to signal the presence of light, because of their deficiency of 11-cis retinal chromophore. The rods will thus continually secrete glutamate neurotransmitter, and after a time the Muller cells will be unable to mop up the excess glutamate. The glutamate levels will build up within the retina, where they will reach neurotoxic levels and the retina will begin to be destroyed.
The RPE65 deficiency would be genetic in origin, and is only one of many proposed possible pathophysiologies of the disease.
Read more about this topic: Bleach And Recycle
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