An international study of nearly 43,000 people has significantly expanded the number of genetic factors which are known to play a role in macular degeneration associated with age (AMD), the leading cause of vision loss among people over the age of 50 years.
Funded by the National Eye Institute (NEI, for its acronym in English), part of the National Institutes of Health (NIH, for its acronym in English), united States, its findings may help improve understanding about the biological processes that lead to AMD and to identify new therapeutic targets for the potential development of drugs.
AMD is a progressive disease that causes the death of photoreceptors of the retina, the cells sensitive to the light in the back of the eye. The damage is more serious occurs in the macula, a small area of the retina that is needed for central vision, sharp necessary for reading, driving and other daily tasks.
there are Currently no treatments approved by the north american agency of the drug (FDA, for its acronym in English) for the most common form of advanced AMD, called geographic atrophy or AMD “dry”. While the therapies for the other form of advanced, neovascular, or “wet”, you can stop with success the growth of abnormal blood vessels leaking in the eye, the therapies do not cure the disease, nor does it work for everyone.
AMD is caused by a combination of genetic risk factors, environmental and life-style. For example, smoking raises the risk of this eye condition, while eating vegetables and fish, green leafy, such as salmon, grouper and tuna, may reduce the risk. Up to this point, the investigators had identified 21 regions of the genome –called loci– that influence the risk of AMD, but the new research, published in the journal ‘Nature Genetics’, it increases the number up to 34 loci.
The International Consortium of Genomics in the AMD, which includes 26 centers in all over the world, collected and analysed the genetic data of 43.566 people ancestry is predominantly european to systematically identify the common variations and rare in the genetic encoding -calls variants– associated with AMD. Common variants usually have an association indirectly with a disease, while rare variants are more likely to alter the expression or function of the protein and, therefore, have a direct association or causal to a disease.
rare variants are defined as those that are found on less than 1 percent of the study population. The research included about 23,000 participants with AMD and 20,000 without it, and the authors analyzed DNA samples of both groups, by inspecting the majority of the genome, but also focused on distinct loci already known or suspected that are associated with AMD.
Then they compared the DNA of the participants with a set of reference data that is called 1,000 Genomes Project, producing more than 12 million genetic variants of potential interest, and finally, returned to the DNA samples from the participants, analyzing the 12 million variants, to see if there are more or less often in people with AMD compared to those who are free of pathology.
researchers have now discovered a total of 52 genetic variants that are associated with AMD, who are among the 34 loci, 16 of which had not been previously associated with age-related macular degeneration associated with age.
“These variants provide a basis for genetic studies of AMD in the future”, says one of the lead authors, Jonathan L. Haines, of the ‘Case Western Reserve University’, in Cleveland, united States. The results of the study reinforce the associations between AMD and two genes, CFH and TIMP3, which had previously been linked to this pathology and its authors also identified a specific variant of the neovascular form of the DAME, which you can point to reasons why the therapy for this form of pathology is effective for some people, but not for all.
in Addition, 10 of the variants point to genes involved in the maintenance of the extracellular matrix, the material is not living between cells that provides structural support and nutrients. Researchers have theorized that abnormalities of the extracellular matrix occur in people with a subtype of AMD that develops without signs in the initial phase, or quickly gets worse before they are detected these signs.
If it is confirmed, a connection between AMD and these genes of the extracellular matrix may allow for genetic testing, predictive and more effective therapies for people with this type of macular degeneration.