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Causes of Retinitis Pigmentosa

written by: VickieDawn • edited by: lrohner • updated: 1/15/2011

The causes of retinitis pigmentosa are mainly hereditary although there are several other factors that can cause the condition. For example, Usher syndrome is one of three conditions known to play a role.

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    Retinitis pigmentosa is a disease that affects the retina of the eye. The retina is located in the back of the inner eye where light is converted into nerve signals. The nerves transmit the signals to the brain that attributes light in the field of vision. When disease strikes the retina, it causes vision loss. The causes of retinitis pigmentosa stem from genetics and heredity. Injury and infection are not a factor in the cause of the condition.

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    About the Condition

    Most cases of retinitis pigmentosa appear in childhood. Doctors can diagnose the condition in children as young as ten. The biggest risk factor is a family history of the condition. It is not a common condition with just 1 in 4,000 being afflicted in the United States according to Medline Plus.

    The retina contains cells called rods and cones. The rod cells detect dim light as in night vision, and cone cells detect light and color. Patients that have retinitis pigmentosa, gradually lose vision because the rods and cones in the retina breakdown and die.

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    Symptoms

    The causes of retinitis pigmentosa stem from heredity exhibited in different ways. One of the first signs of retinitis pigmentosa is decreased night vision. As the condition progresses and the rods and cones die off, eye sight becomes more difficult. Vision will progressively worsen from poor night vision to tunnel vision, a manifestation of rod-cone dystrophy. Peripheral vision is lost until a small center vision exists. Many of these patients retain some central vision.

    Another type of retinitis pigmentosa is the breakdown of the central vision field. Some patients experience cone-rod dystrophy, reflected in the loss of the central vision.

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    Causes

    The majority of people suffering from retinitis pigmentosa were programmed before birth. The causes of the condition narrows down to heredity and genetics. There are several genetic factors, each influencing the condition. One is a recessive gene carried by both parents. Another is a dominant gene or genes on an X chromosome.

    Mutant genes can cause the condition without the heredity factor. Mutating genes are still a mystery to researchers and are difficult to predict.

    There is a ten percent possibility that some people with retinitis pigmentosa will be deaf.

    Usher syndrome affects 12 percent of children that are deaf or hard of hearing. The syndrome is genetic with the defective gene carried by the parents.

    There are two other sources that cause retinitis pigmentosa which are Bassen-Kornzweig disease and Kearns-Sayre syndrome. Bassen-Kornzweig is caused by the inability to digest certain vitamins and fats. Kearns-Sayre syndrome is a neuro-muscular disorder.

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    There is not much a person can do to avoid the condition since the causes of retinitis pigmentosa are primarily hereditary. Experiments are on-going for transplant and electro-therapy. Protecting the eyes from light and taking vitamin A, are some treatments used by clinicians but nothing has proven to improve vision or keep the condition from progressing. Genetic testing is a consideration for parents to see if they carry the gene.

    To keep us with the latest research and treatments, visit the RP International and Foundation Fighting Blindness websites.

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    References

    United States National Library of Medicine Medline Plus: Rentinitis Pigemntosa

    http://www.nlm.nih.gov/medlineplus/ency/article/001029.htm

    National Human Genome Research Institute: Retinitis Pigmentosa

    http://www.genome.gov/13514348

    Wills Eye Hospital: Retinitis Pigmentosa

    http://www.willseye.org/patients/topics/retina/rp/index.html

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    Resources

    Foundation Fighting Blindness

    http://www.blindness.org/

    RP International

    http://www.rpinternational.org/