Featured Research

from universities, journals, and other organizations

UIC Researchers Find Molecular Clue To Genetic Diseases

Date:
December 22, 1997
Source:
University Of Illinois At Chicago
Summary:
Scientists at the University of Illinois at Chicago have found an important molecular clue to genetic diseases caused by expansions of repeated DNA segments. They have shown that the lengths of the segments and the status of protein synthesis in a cell affect their replication.

Scientists at the University of Illinois at Chicago have found an important molecular clue to genetic diseases caused by expansions of repeated DNA segments.

They have shown that the lengths of the segments and the status of protein synthesis in a cell affect their replication. Researchers found that when the number of repeated segments exceeded a threshold, abnormal replication occurred. Their discovery could eventually set the stage for finding possible ways to block DNA mutations that result in disease.

The findings of the UIC research team, led by Sergei Mirkin, associate professor of molecular genetics, were published in the November issue of the journal Nature Genetics. The research was supported by grants from the National Science Foundation and the Council for Tobacco Research.

Individuals affected by disease carry hundreds, sometimes thousands of repeats of certain trinucleotides, while normal individuals carry only about five to 30 repeats. As a result of this expansion, the affected human genes do not function, resulting in disease. More than a dozen human disorders -- including a common form of mental retardation, Huntington's disease, myotonic dystrophy and several hereditary neurological diseases (ataxias) -- are now attributed to the expansion of repeats of certain trinucleotides in different human genes.

Mirkin and his colleagues, genetics postdoctoral fellow George Samadashwily and genetics graduate student Gordana Raca, analyzed the effects of various lengths of the trinucleotide repeats (CGG)n/(CCG)n and (CTG)n/(CAG)n on the replication of plasmids (small rings of DNA) in bacterial cells. They cloned long stretches of the trinucleotide repeats and used a sophisticated technique called two-dimensional gel electrophoresis to detect intermediate steps of DNA replication.

They found that the replication process of the repeated DNA segments is abnormal. When the number of uninterrupted repeats exceeded a critical threshold -- 30 to 50 repeats -- the replication process is temporarily stalled by the lengthy repeated segments. And, they found the greater the number of repeats above that threshold, the longer the stall, possibly resulting in an abnormal number of repeated segments being produced.

"Replication of the repeated segments took as much as ten times longer than it should have," says Mirkin. "We hypothesize that the abnormal expansion of the repeated segments occurs at this stalling point. "It's as if a car hits a large hole in the road, gets stuck and has to spin its wheels extensively to get out."

Mirkin adds that the mechanism that causes this replication blockage and subsequent expansion is not known yet. "Once that is understood, we can try to develop ways to bypass that roadblock and make the replication process go smoothly and thus avoid diseases," says Mirkin.

Mirkin sees significant future implications for this line of research. "We would expect to see many more diseases explained by this abnormal DNA replication process. We believe this expansion may occur in many other DNA repeats that are seen in many other diseases such as diabetes and epilepsy. In a sense, genetic diseases are a side product of the complexity of the DNA replication process, where genetic alterations almost inevitably occur."


Story Source:

The above story is based on materials provided by University Of Illinois At Chicago. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Chicago. "UIC Researchers Find Molecular Clue To Genetic Diseases." ScienceDaily. ScienceDaily, 22 December 1997. <www.sciencedaily.com/releases/1997/12/971222114619.htm>.
University Of Illinois At Chicago. (1997, December 22). UIC Researchers Find Molecular Clue To Genetic Diseases. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/1997/12/971222114619.htm
University Of Illinois At Chicago. "UIC Researchers Find Molecular Clue To Genetic Diseases." ScienceDaily. www.sciencedaily.com/releases/1997/12/971222114619.htm (accessed August 1, 2014).

Share This




More Health & Medicine News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Quintuplets Head Home

Texas Quintuplets Head Home

Reuters - US Online Video (Aug. 1, 2014) After four months in the hospital, the first quintuplets to be born at Baylor University Medical Center head home. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Patient Coming to U.S. for Treatment

Ebola Patient Coming to U.S. for Treatment

Reuters - US Online Video (Aug. 1, 2014) A U.S. aid worker infected with Ebola while working in West Africa will be treated in a high security ward at Emory University in Atlanta. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
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