Featured Research

from universities, journals, and other organizations

Long-suspected cause of blindness from eye disease disproved

Date:
March 11, 2013
Source:
University of Utah Health Sciences
Summary:
The lack of very long chain fatty acids does not cause blindness in children with the incurable eye disease known as Stargardt type 3 retinal degeneration.

Vision scientists long have thought that lack of very long chain fatty acids in photoreceptor cells caused blindness in children with Stargardt type 3 retinal degeneration, an incurable eye disease. But researchers at the University of Utah's John A. Moran Eye Center have shown in a new study that lack of these fatty acids does not cause blindness, meaning that the search for the mechanism that robs children of their sight must start anew.

Researchers led by David Krizaj, Ph.D., associate professor of ophthalmology and visual sciences at the Moran Eye Center, bred mice that lacked fatty acids in their photoreceptor cells and to their surprise found that the mice's eyesight was normal. "There was no defect in their daytime or nighttime vision," Krizaj says. "The lack of very long chain fatty acids does not appear to compromise vision in itself."

The research was published March 11, 2013, in PNAS online. Peter Barabas, Ph.D., a postdoctoral fellow at the Moran Eye Center, is first author on the study.

Stargardt disease is a form of macular degeneration that strikes about one in 10,000 children between the ages of 6 and 20. There is no treatment for the disease, although there is evidence that nutrition supplements and protecting eyes from UV rays might be beneficial in slowing the progression of blindness.

There are three types of Stargardt disease caused by three different gene mutations. (Paul Bernstein, M.D., Ph.D., professor of ophthalmology and visual sciences and a co-author in the PNAS study, discovered one of the mutations in a Utah family.) Type 3, a rare dominant form of Stargardt disease, is caused by a mutation in ELOVL4, a gene that encodes an enzyme that helps to make fatty acids obtained through our diet into forms that can be incorporated into cell membranes. The mutation displaces the enzyme from its location in the cell's network of tubules and sacs, called the endoplasmic reticulum, into cellular liquid known as cytosol, which blocks the synthesizing of very long chain fatty acids in photoreceptor cells. But proving that the lack of these fatty acids actually causes blindness has been difficult to show in experiments because mice in which ELOVL4 was knocked out did not survive.

Krizaj and his colleagues overcame that problem by engineering mouse models that lacked ELOVL4 only in their photoreceptor cells, allowing the mice to survive but with the fatty acids in those cells reduced up to 90 percent. This allowed the researchers to test directly whether loss of very long chain fatty acids replicates vision loss observed in children with Stargardt's disease. As they report in the journal, electrophysiological and behavioral testing of daytime and night vision in genetically engineered mice showed that sight was not affected despite the dramatic reduction in very long chain fatty acids in photoreceptor cells.

Researchers now must look for a different cause of Stargardt type 3. "If it's not the loss of fatty acids causing the disease, then we'll have to find other strategies to help these kids," Krizaj says.

One possibility is that mutated proteins escaping from the endoplasmic reticulum are aggregating in the cytoplasm, a jelly-like substance in the cell, and resulting in large deposits of mutated and normal proteins. "This is almost like causing photoreceptor cell death by blocking intracellular traffic and clogging the cells' drains," Krizaj says.


Story Source:

The above story is based on materials provided by University of Utah Health Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Barabas, A. Liu, W. Xing, C.-K. Chen, Z. Tong, C. B. Watt, B. W. Jones, P. S. Bernstein, D. Krizaj. Role of ELOVL4 and very long-chain polyunsaturated fatty acids in mouse models of Stargardt type 3 retinal degeneration. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1214707110

Cite This Page:

University of Utah Health Sciences. "Long-suspected cause of blindness from eye disease disproved." ScienceDaily. ScienceDaily, 11 March 2013. <www.sciencedaily.com/releases/2013/03/130311173349.htm>.
University of Utah Health Sciences. (2013, March 11). Long-suspected cause of blindness from eye disease disproved. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2013/03/130311173349.htm
University of Utah Health Sciences. "Long-suspected cause of blindness from eye disease disproved." ScienceDaily. www.sciencedaily.com/releases/2013/03/130311173349.htm (accessed July 29, 2014).

Share This




More Health & Medicine News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Two Americans Contract Ebola in Liberia

Two Americans Contract Ebola in Liberia

Reuters - US Online Video (July 28, 2014) Two American aid workers in Liberia test positive for Ebola while working to combat the deadliest outbreak of the virus ever. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins