New Causes of Macular Degeneration: Genetic Discovery

genes

Image courtesy of: microbialgenomics.energy.gov

Researchers at the University of Manchester are making strides as they begin to understand another cause of macular degeneration.

Five years ago, scientists discovered that people who developed macular degeneration had a variant form of the gene CFH, a protein involved in the regulation of the immune system.  In this new study it was found that people with this variant gene are more susceptible to inflammation within the eye that could eventually lead to the damage of cells and the development of macular degeneration.

Understanding the problem on the molecular level will hopefully lead to new therapies, according to those on the research team.

Source: http://media-newswire.com

Other scientists have  identified a another variant possessed by 20 percent of the population that can actually protect people against AMD.

Source: http://www.technologyreview.com/

Update:  alu RNA

“Geographic atrophy,” which causes cell death in the retina of the eye, is blamed as a major cause of what is often described as untreatable blindness and is  associated with dry macular degeneration.

Researchers publishing in the journal Nature find a DNA level cause for macular degeneration: non-coding “junk DNA” that was previously thought to have no function.  The scientists also found that another genetic component, RNA in a toxic form called Alu RNA, is also involved in retinal cell death.

These two discoveries could open new doors for therapies for macular degeneration patients.  Source: http://www.medicalnewstoday.com

Update: Hepatic Lipase Gene Connection

In an analysis of the genes of more than 1,000 patients with AMD, an international team of scientists discovered a strong association between the vision problem and the presence of a new gene.

The new gene connection is with hepatic lipase gene LIPC, a critical enzyme in the metabolism of high-density lipoprotein (HDL). The study also noted strong associations between advanced AMD and other single nucleotide polymorphisms in the same lipid pathway, but the other finding showed a much stronger, genome-wide significance.

Abstract Title: Genome-Wide Association Study of Advanced Age-Related Macular Degeneration Identifies a New Susceptibility Locus in the Lipid Metabolism Pathway, Hepatic Lipase (LIPC)

Update: Efemp1 Gene

Researchers at the University of Pennsylvania School of Medicine have created the first animal model of age-related macular degeneration (AMD) caused by a mutation known to produce disease in people.

AMD is the most common cause of vision loss in elderly people, affecting more than 10 million people in the U.S. and about 50 million world-wide. Because AMD develops late in life (patients typically show symptoms of AMD after age 60), it is a difficult condition to investigate.

Although some forms of AMD are inherited, one type is thought to be caused by a mutation in the Efemp1 gene. Researchers introduced the disease-causing mutation into the Efemp1 gene of mice. These Efemp1-mutant mice develop the same basal deposits as people with AMD.

It is believed that these mice will provide a means to study how basal deposits form and what they are made of. The mice can also be used to test potential treatments to prevent basal deposit formation.

“To better develop treatments for preventing the progression of AMD, we need to understand the real biochemical details of how AMD occurs,” says lead author Eric A. Pierce, MD, PhD, Associate Professor of Ophthalmology at Penn’s K.M Kirby Center for Molecular Ophthalmology. “To do that, we need a model, and now we have one.”

SOURCE: Model To Study Age-related Macular Degeneration Could Pave Way For Better Treatment, Pierce et al, University of Pennsylvania School of Medicine (2007, October 10).