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| printer friendly | LEBER'S HEREDITARY OPTIC NEUROPATHY | ||||||||||||||||||||
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You can access the trial website at Web: http://lhon.ncl.ac.uk Leber's Hereditary Optic Neuropathy: Leber's Optic Atrophy: LHON This is a rare inherited condition which involves the optic nerves with either complete or partial loss of central vision. This disorder is unrelated to Leber's Congenital Amaurosis - the only connection being that they were described by the same doctor. The optic nerve is the "information cable" joining the eye, the "camera", to the brain. If damage occurs to the retina or the optic nerve then some of the "wires" in the optic nerve will die. The "finest wires" that allow us to see fine detail are lost in LHON. The nerve health can be assessed by looking into the eye. A healthy nerve looks pink and one that has been damaged pale and is called "atrophic". However, early in LHON the nerve can look abnormally pink and slightly swollen. The genetic defect is in the mitochondria, small bodies inside cells that generate their energy. Normally males lose their eyesight between the ages of fifteen to forty-five, but visual loss may occur in young children or later in life. Often vision is lost in one eye a few months before the other. There may be spontaneous marked improvement in vision several months or even years after abrupt severe vision loss. This observation makes it difficult to assess efficacy of any treatments. There is loss of central vision and diminished colour vision. Children will have difficulty with reading and fine detail tasks especially with low contrast and small detail work. Several studies have shown increased risk of vision loss in smokers, in heavy alcohol drinkers and in those with diets deficient in natural antioxidants (substances that inhibit oxidation or reactions promoted by oxygen). The value of vitamin supplementation to a normal diet is not of proven value. There is some evidence of a possible benefit of drugs including steroids and Idebenone in acute disease. Very rarely individuals have other problems including mild neurological symptoms and cardiac conduction defects with irregularity of heart beat. Inheritance patterns Genetic testing in one of UK's National reference laboratories, Web: http://www.lwh.nhs.uk/genetics/molecular/services.html is available for adults who may be asymptomatic but who have a close relative with LHON and who wish to know if they are at risk of developing symptoms and their risk of passing on the genetic defect. Genetic testing is only advised for children with visual loss in whom a diagnosis of LHON is being considered on clinical signs. The mutation (spelling mistake in the DNA) can be detected in about ninety per cent cases thought clinically to have LHON. The majority have one of the following mutations: 11778, 3460, 14484. Whilst symptomatic individuals with 14484 generally have better vision outcome there is much variation even within each group. Many individuals with these genetic defects, especially females, may have normal vision throughout life. At the moment there is no way of predicting which people carrying a LHON gene will actually go on to lose their eyesight, or how badly their eyesight will be affected. Prenatal diagnosis Medical text written October 2004 by Miss Isabelle Russell-Eggitt FRCS FRCOphth, Consultant Ophthalmic Surgeon, Great Ormond Street Hospital for Children, London, UK. ![]() Further Online Resources There is currently no effective support group covering Leber's Hereditary Optic Neuropathy. This medical description is retained for information purposes. Families can use Contact a Family's Freephone Helpline for advice, information and, where possible, links to other families. Contact a Family's web-based linking service Making Contact.org can be accessed at http://www.makingcontact.org |
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| This Web Site © Copyright, Contact a Family 2007. Although great care has been taken in the compilation and preparation of this work to ensure accuracy, Contact a Family cannot accept responsibility for any errors or omissions. Any medical information is provided for education/information purposes. It should be noted that most information written about specific disorders includes the most severe scenario. Many individual cases may not display all the features mentioned and the degree of severity of the features that are displayed may vary a great deal between individual cases. You should obtain further information from your medical practitioner. Any links to external websites have been carefully selected but are provided without any endorsement of the content of those sites. Please refer to our detailed Legal page for more information. Contact a Family, 209-211 City Road, London EC1V 1JN Tel: (020) 7608 8700. Registered Charity No. 284912. Company limited by guarantee, registered in England and Wales No. 1633333. HM Revenue & Customs charity tax reference No. XN54769. VAT Reg. No. GB 749 3846 82. |
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