Featured Research

from universities, journals, and other organizations

Unexplained intellectual disability explained by state-of-the-art genetic analysis

Date:
November 8, 2012
Source:
American Society of Human Genetics
Summary:
A research team reported that next generation sequencing of the exome, the one to two percent of the DNA containing the genes that code for proteins, enabled the identification of the genetic causes of unexplained intellectual disability in over 50 percent of patients in a study.

A research team reported that next generation sequencing of the exome, the 1 to 2% of the DNA containing the genes that code for proteins, enabled the identification of the genetic causes of unexplained intellectual disability in over 50% of patients in a study conducted at Radboud University Medical Centre in Nijmegen, The Netherlands.

"Through next generation sequencing, we were able to discover mutations in genes that had not been previously linked to causing intellectual disability," said Marjolein Willemsen, M.D., Ph.D., who presented the research at the American Society of Human Genetics 2012 meeting in San Francisco on November 8.

Correctly diagnosing children with intellectual disability (ID) can lead to early intervention and special education programs, vocational training and health screenings for associated conditions that will enable them to reach their full potential, said Dr. Willemsen of Radboud's department of human genetics.

Genetic diagnosis "is of major importance for the care and counseling of patients and families," Dr. Willemsen said. "Proper diagnosis provides insight into associated health and behavioral problems, prognosis and recurrence risk."

The cause of intellectual disability is unknown in more than half of patients with learning and other intellectual disabilities, which affect about 2% of the population, said Tjitske Kleefstra, M.D., Ph.D., also of Radboud University Medical Centre's human genetics department.

Participating in the Radboud University study were 253 patients with unexplained intellectual disability, most of whom were adults. They underwent a multidisciplinary clinical evaluation and a metabolic screen. Genome-wide analysis of each patient's DNA was also conducted, and specific genetic diagnostic tests were performed as needed.

Because they used both genetic tests and clinical evaluations, the researchers were able to correlate the biological as well as the behavioral features of each patient's intellectual disability with the DNA findings.

Intellectual disability can be a challenge to diagnose because a wide range of features characterizes these disorders, and the underlying genetic causes can vary widely, Dr. Kleefstra said. "As a result, many parents go from one doctor to another in search of a diagnosis and treatment for their child," she added.

In the first part of the study, a diagnosis was made in over 18% of the patients as a result of the combination of clinical evaluation and application of genetic diagnostic technologies that are now routinely used in clinical genetic practice.

Many of the identified mutations were chromosomal abnormalities, and 5% were mutations in single genes that already had been linked to ID. One of these genes, EHMT1, was discovered in 2006 by Dr. Kleefstra as the cause of what is now known as the Kleefstra syndrome, which is characterized by intellectual disability, hypotonia (low muscle tone) and distinctive facial appearance.

The researchers then performed next generation sequencing (NGS) in a subset of the patients who remained undiagnosed after the first analysis. In this second part of the study, the exomes of the included patients were analyzed.

In 17 of the 47 patients (36.2%) in whom NGS was applied, the likely pathogenic genetic causes were identified. The total yield of both parts of the study thus totaled over 54%.

Because intellectual disability syndromes caused by several novel genes were identified, the study has expanded scientific knowledge about the range of genetic causation in intellectual disability, Dr. Willemsen said.


Story Source:

The above story is based on materials provided by American Society of Human Genetics. Note: Materials may be edited for content and length.


Cite This Page:

American Society of Human Genetics. "Unexplained intellectual disability explained by state-of-the-art genetic analysis." ScienceDaily. ScienceDaily, 8 November 2012. <www.sciencedaily.com/releases/2012/11/121108141020.htm>.
American Society of Human Genetics. (2012, November 8). Unexplained intellectual disability explained by state-of-the-art genetic analysis. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/2012/11/121108141020.htm
American Society of Human Genetics. "Unexplained intellectual disability explained by state-of-the-art genetic analysis." ScienceDaily. www.sciencedaily.com/releases/2012/11/121108141020.htm (accessed September 23, 2014).

Share This



More Health & Medicine News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Liberia Pleads for Help to Fight Ebola

Liberia Pleads for Help to Fight Ebola

AP (Sep. 22, 2014) Liberia's finance minister is urging the international community to quickly follow through on pledges of cash to battle Ebola. Bodies are piling up in the capital Monrovia as the nation awaits more help. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Ebola Doctor Says Border Controls Critical

Ebola Doctor Says Border Controls Critical

AP (Sep. 22, 2014) A Florida doctor who helped fight the expanding Ebola outbreak in West Africa says the disease can be stopped, but only if nations quickly step up their response and make border control a priority. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Global Ebola Aid Increasing But Critics Say It's Late

Global Ebola Aid Increasing But Critics Say It's Late

Newsy (Sep. 21, 2014) More than 100 tons of medical supplies were sent to West Africa on Saturday, but aid workers say the global response is still sluggish. Video provided by Newsy
Powered by NewsLook.com
Sierra Leone in Lockdown to Control Ebola

Sierra Leone in Lockdown to Control Ebola

AP (Sep. 21, 2014) Sierra Leone residents remained in lockdown on Saturday as part of a massive effort to confine millions of people to their homes in a bid to stem the biggest Ebola outbreak in history. (Sept. 20) 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:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

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