Stargardt’s disease - defective gene threatening your vision, are you aware?

Stargardts-DiaeaseStargardt’s Disease is an autossomal recessive hereditary disease included in the group of degenerative macular diseases, which consists in progressive lost of cones in fovea of both eyes, leading to variable levels of central vision loss. At fundoscopy, there’s often the presence of yellowish flecks around the macula, a condition called fundus flavimaculatus.

It usually develops in ages between 7 and 12, with an estimated incidence between 1/1660 and 1/15000, what makes this disease the largest cause of macular degeneration affecting the retinal pigment epithelium (RPE) in the first and second decades of life, and correspond to 7% of all retinian dystrophies.

This disease was first described as an autossomal recessive inherited disease, but there are some described cases of dominant pattern. The recessive pattern, which includes more than 90% of cases, is due to a defect at the chromosome 1q21-p13. The dominant pattern seems to be related to a change at chromosome 6, but some studies also reported the location on chromosome 12. The altered gene seems to be responsible for the transcription of protein that works like an outer molecular pump.

The foveal damage is possibly due to a defect on an outer molecular pump that would eliminate a specific substance from cones. This molecule builds up inside the rods, accumulating as a form of lipofuscine, which penetrates in the RPE, acting as a poisoning substance for this layer, making it susceptible to lysis. The photoreceptor layer in the fovea demands an enormous fagocytic and metabolic activity from the RPE (much greater than in periphery), what makes the atrophic changes in Stargardt’s Disease be found mainly at foveal area. Fundus Flavimaculatus happens as a consequence of the atrophic epithelium of the central area, that becomes hyperfluorescent, and the still intact epithelial cells immersed in lipofuscin, which absorbs the blue excitatory wave-lengths, making this perifoveal region hypofluorescent in pisciform shapes(corresponding to the fresh flecks at fundoscopy).

The degeneration process begin early , normally at 7 years old, being the foveal reflexes alteration with granulous aspect of RPE the first manifestation. Hardly the disease is diagnosed at this age due to low age of patients. These lesions progress with macular and perimacular atrophy of RPE. The yellowish flacks can be observed around the macula characterizing the fundus flavomaculatus .

mv-v14-262-f1The visual effect of disease consists in a loss of central visual responsible for visual acuity and color perception. Usually it evolutes slowly until reaches the 20/40 level, then rapidly progressing to something around the 20/200 level. It leads to variable levels of visual loss , up to a 10/200 level or less. In some cases, it can in a period of months evolute from 20/40 to 10/200 , but it do not lead to complete blindness.

The presence of a defect in green-red axis color perception and a progressing central scotoma are the other common features of affected patients.

There is no treatment that proved to improve the visual loss or to retard the progressing of the disease. There are a few measures that should be adopted and that will help the patients solving some of the problems that they face. There are many kinds of binocular lens, either for improving near vision or distance vision, increase the visual field, protect against the light, watching, looking at the blackboard and improving the reading of the patients; the choose of the most useful lens for each patient should be performed by the physician and the patient together. the More affected persons should learn to read in Braille, and have the other specific management for low vision conditions. A great number of the affected patients will be classified as owing legal blindness. Some doctors recommend the use of vitamins, in special A, E, C, Selenium and Betacarotene.

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6 Responses to “Stargardt’s disease - defective gene threatening your vision, are you aware?”

  1. Ed Joehnk Says:

    You inferrance will accelerate the damage to the retinas of Stargardts patients;
    part of your article details correctly that the build up metabolite waste products poisons the cell.

    Then your last sentance counter acts;
    “Some doctors recommend the use of vitamins, in special A, E, C, Selenium and Betacarotene.”

    Vitamin A and all the carotene anologs are the main source of these waste products. It is better to run the eyes starved of these drivers of vision mechanisms so that the remaining waste removal system that still works can keep up with the waste load generated.

    No vitamin A supplements, no colored fruits or veggies. In fact there is a group that is proposing a medication to remove excess vitamin A out of the blood stream for this purpose.

    Ed Joehnk, chemist father of a Stargardts child.

  2. Michael Edson, MS, L.Ac. Says:

    It is very likely that a diet strong in leafy green vegetables may be protective to the retina. During the winter, if fresh fruits and vegetables are limited, a multivitamin that has vitamins A, E, and C may be useful. These vitamins are thought to act as “anti-oxidants” and protect against light damage in the eye. A diet that includes fish at least twice weekly may also be helpful - as fish contains omega-3 fatty acids, especially docosahexaenoic acid (DHA) which is found in high concentration in the normal retina.

  3. sourish Says:

    Thanks for replying. I want to suggest one thing to you since, you know this disease is gene related so the treatment should be mainly based on gene therapy. Moreover, addition of Vit A is a general treatment for eyes, which keeps the eyes in good health. Vit A in no way adds up to the substances in outer molecular pump, only defective proteins cause it.
    Have a nice day.

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  5. John Hasenkam Says:

    Vitamin A and all the carotene anologs are the main source of these waste products. It is better to run the eyes starved of these drivers of vision mechanisms so that the remaining waste removal system that still works can keep up with the waste load generated.

    No vitamin A supplements, no colored fruits or veggies. In fact there is a group that is proposing a medication to remove excess vitamin A out of the blood stream for this purpose.

    Ed Joehnk, chemist father of a Stargardts child.

    Exactly, there is now a general warning that people with Stargardts should montior their Vit A intake very carefully. There is even a study showing that excess vit A in the animal mode of STGD rapidly accelerated visual decline.

    My general advice is to keep VIT A and beta carotene to the very low side of normal. The mammalian visual cycle is NOT light dependent, it consistently turns over and this is related to vit A availability. Reducing visual cycle turnover appears to be very important. Do not completely eliminate VIT A as this will cause more problems than it solves. Ideally, blood tests are probably the best way to go.

    Ed,

    Thanks for your post, you clearly have done your homework. Some time ago friends approached me after their daughter was diagnosed with STGD. We developed a therapy and since that time (18 months) her visual acuity and retinal condition has stabilised whereas prior to our therapy she demonstrated a similiar rate of decline to her first 2 cousins who have the condition. It is very early days yet and one case is not that indicative but our approach was very much based on the available data and an understanding of retinal metabolism and the visual cycle.

    Thanks for your post, good to see some people are actually thinking about this at a detailed level rather than opting for a generalised “vit a is good for the eyes therefore … “.

  6. Xtend life skin care Says:

    For the most part, vitamins are obtained with food, but a few are obtained by other means. For example, microorganisms in the intestine�commonly known as “gut flora”�produce vitamin K and biotin, while one form of vitamin D is synthesized in the skin with the help of the natural ultraviolet wavelength of sunlight.

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