Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gene Variant Increases Risk of Age-Related Macular Degeneration

11.03.2005


Researchers at Duke University Medical Center and Vanderbilt University Medical Center have pinpointed the first major gene that determines an individual’s risk for developing age-related macular degeneration (AMD). The chronic, progressive disease -- which affects as many as 15 million people in the United States -- is the leading cause of visual impairment and legal blindness in the elderly.



A common variant of the gene, called complement factor H (CFH), explains approximately 43 percent of the risk of AMD among older adults, the researchers estimated. The team identified the disease-related gene after screening 182 families affected by AMD and 495 other individuals with the condition. The researchers will report their findings in a forthcoming issue of Science (published online March 10, 2005, in Science Express).

The genetic advance sheds light on the mechanisms underlying the disease and could lead to new avenues for treatment, the researchers said. The finding might also yield methods for identifying those patients at the greatest risk for developing the condition before symptoms arise, when therapies and changes in lifestyle might be most effective in slowing the disease progression. "Macular degeneration is an important cause of blindness and loss of independence in the elderly," said Margaret Pericak-Vance, Ph.D., director of the Duke Center for Human Genetics and senior author of the report. "This gene opens the door to a whole new understanding of the factors that contribute to this disease. "The finding may ultimately lead to new methods for identifying those at high risk for macular degeneration and suggests new pathways for drug development," she added.


AMD causes progressive impairment of central vision, and is the most common cause of legal blindness in Americans over the age of 55. The disease causes damage to the retina, a thin layer of nervous tissue that lines the inside of the eye. The primary site of damage occurs in the central retina, a portion called the macula.

The retina functions like film in a camera, explained ophthalmologist Eric Postel, M.D., of the Duke University Eye Center. Without proper retinal function, images cannot be captured and sent to the brain. The macula is critical for fine, detailed vision. In patients with severe AMD, progressive blurring and loss of central vision due to damage of the macula may leave people unable to perform everyday activities such as driving, reading, writing checks and recognizing faces, he said. "Fifteen million people in the United States have AMD and 1.5 million have the most severe form," said Postel, the head clinician on the study. "By the year 2030, as the baby boomer generation ages, the number of people with AMD is expected to double."

AMD exists in two forms: the "dry" form and more severe "wet" form. In the dry form, degeneration of the macula can cause slow, progressive vision loss over the course of months to years. While there is no cure, vitamin supplements have been shown to slow the disease in some individuals with this milder form.

In ten percent of patients, the disease progresses to the wet form in which abnormal blood vessels under the macula leak blood and fluid causing rapid damage and a precipitous loss of vision. Patients with wet AMD can receive several treatments to prevent further vision loss -- including laser surgery and recently approved injections of a drug into the eye. However, available therapies usually can only stall the disease progression, Postel said. None effectively reverse the course of the disease.

While the underlying causes of AMD had remained largely unknown, risk factors include age, smoking, high blood pressure, obesity and diet, said Pericak-Vance. In addition to such environmental factors, evidence from family and twin studies had indicated a significant genetic contribution to the disease, she added.

Earlier studies by the Duke and Vanderbilt teams and others had linked AMD risk to a particular region on chromosome 1. To identify the gene responsible, the researchers examined two independent data sets: the first contained 182 families including members with and without AMD and the second contained 495 individuals with AMD and 185 unrelated individuals not affected by the disease.

The researchers zeroed in on a smaller region of chromosome 1 with a strong association to the disease in both data sets. Further DNA sequencing of the CFH gene that is within that region revealed that individuals with one or more copies of a particular gene variant were more likely to have AMD compared to those with other versions of the gene, they reported. When the researchers restricted the analysis to individuals with the more severe, wet form of AMD, the association between the gene variant and the disease became even stronger.

The researchers estimated that the CFH variant may be responsible for up to 43 percent of all cases of AMD. Earlier studies had suggested that CFH may play a role in protecting blood vessels from inflammation and damage, a function which might explain its role in AMD, the researchers said. "We knew that chronic inflammation played a role in macular degeneration, but we didn’t know if that was a primary cause of the disease or a secondary symptom," said Jonathan Haines, Ph.D., of Vanderbilt Center for Human Genetics Research and first author on the report. "The finding that complement factor H is an important contributor to the disease suggests that inflammation may be a more important aspect of the disease than had previously been appreciated."

Given that the gene plays such a large role in AMD, further studies of CFH and the cellular components with which it interacts might lead to a rapid increase in understanding of the biology of the disease, the researchers added. That information, in turn, should allow scientists to advance on new treatments and preventive therapies.

Collaborators on the study include Michael Hauser, Silke Schmidt, William Scott, Paul Gallins, Shu Ying Kwan, Maher Noureddine and John Gilbert, of the Duke Center for Human Genetics; Lana Olson, Kylee Spencer, Nathalie Schnetz-Boutaud and Anita Agarwal, of the Vanderbilt University Medical Center. The National Eye Institute supported the work. Additional resources came from the National Institute on Aging and the National Center for Research Resources to Vanderbilt University.

Kendall Morgan | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

nachricht How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>