What is Leber congenital amaurosis?
Leber congenital amaurosis (LCA) is an inherited form of blindness that is usually apparent shortly after birth. In most cases, affected children are otherwise completely healthy but a subset of children do have other problems such as learning disabilities, autism, seizures, or kidney disease. At least nine different genes are currently known to cause the disease and as a group these genes are responsible for about 70% of all cases. There have been some very exciting developments regarding treatment for LCA. Years of research led to treatments to restore vision in animals with similar disorders and last year (2009) the first human clinical trials met with similar success. It is expected that more treatments will soon be ready for testing in human beings and for most of these treatment trials knowledge of the disease-causing gene will be important.
What are the symptoms of LCA?
Individuals with LCA have very reduced vision at birth. Within an infant’s first few months of life, parents usually notice a lack of visual responsiveness and unusual roving eye movements, known as nystagmus. Eye examinations of infants with LCA reveal normal appearing retinas. However, electroretinography (ERG) tests, which measure visual function, detect little if any activity in the retina. A low level of retinal activity, measured by ERG, indicates very little visual function.
By early adolescence, various changes in the retinas of patients with LCA become readily apparent. Blood vessels often become narrow and constricted. A variety of pigmentary (color) changes can also occur in the retinal pigment epithelium (RPE), the supportive tissue underlying the retina. Sometimes, pigmentary changes are similar to another retinal degenerative disease known as retinitis pigmentosa.
Although the appearance of the retina undergoes marked changes with age, vision usually remains fairly stable through young adult life. Long term visual prognosis remains to be defined. Visual acuity in patients with LCA is usually limited to the level of counting fingers or detecting hand motions or bright lights. Some patients are also extremely sensitive to light (photophobia). Patients with remaining vision are often extremely farsighted.
Source: Foundation Fighting Blindness
Is there a genetic test available?
Yes. The John and Marcia Carver Nonprofit Genetic Testing Laboratory has released a clinical nonprofit test for Leber congenital amaurosis. See Genetic Tests We Offer
How can I order a genetic test for LCA?
You can start by requesting a test with the CNGTL. You may also want to look at special instructions for Project 3000 participants.
Is there a clinical trial available for this particular condition?
Research regarding the eye and blinding eye diseases is ongoing and the answer to this question might change on any given day. Thankfully there are resources available today to assist anyone interested in monitoring progress.
Where can I learn more about Leber congenital amaurosis?
GeneTests is a publicly funded web site that provides medical genetics information. While primarily targeted to physicians, researchers and other healthcare providers, patients and their families interested in a reliable resource for their own research will find this up-to-date comprehensive web site an invaluable tool. See Leber congenital amaurosis as found on GeneTests.org
The Genetic and Rare Diseases Information Center (GARD), a collaborative effort of two agencies of the National Institutes of Health: The Office of Rare Diseases Research (ORDR) and the National Human Genome Research Institute (NHGRI), is another most excellent resource.
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If you have any specific questions about Leber congenital amaurosis, please consult your personal physician.
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