Featured Research

from universities, journals, and other organizations

Genetic component of autism spectrum disorders may be moderate compared to environment, twin study suggests

Date:
July 4, 2011
Source:
JAMA and Archives Journals
Summary:
After evaluating twin pairs in which at least one child has autism or autism spectrum disorder (ASD), researchers suggest that the shared environment may play a more substantial role in development of the condition than shared genes do, according to a new study.

In a new study of twins in which at least one child has autism or autism spectrum disorder (ASD), researchers suggest that the shared environment may play a more substantial role in development of the condition than shared genes do.
Credit: iStockphoto/Sharon Dominick

After evaluating twin pairs in which at least one child has autism or autism spectrum disorder (ASD), researchers suggest that the shared environment may play a more substantial role in development of the condition than shared genes do, according to a report published Online First by Archives of General Psychiatry, one of the JAMA/Archives journals.

Current estimates suggest that 40 of every 10,000 children have autism, and prevalence rates for ASDs are about 1 percent, according to background information in the article. Studies of siblings have found a concordance rate (the likelihood that if one child has the disorder, others will as well) of up to 14 percent. The authors note that in previous studies of twins, concordance rates for autism were relatively high for identical (monozygotic) twins, but nonexistent for fraternal (dizygotic) twins. Further, studies that depended on differing methods of diagnosis have resulted in a broad range of estimates of autism's heritability. "However," the authors state, "none of these more recent studies included structured clinical assessments by both parental interview and direct child observation, which is the contemporary standard for establishing the diagnosis of autism or ASD."

In the California Autism Twins Study, Joachim Hallmayer, M.D., from Stanford University School of Medicine, Palo Alto, Calif., and colleagues used data from the California Department of Developmental Services to identify potential participants. The researchers assessed twin pairs in which at least one child had an ASD diagnosis, using the Autism Diagnostic Interview-Revised, a structured parent interview and the Autism Diagnostic Observation Schedule, as well as other tests to determine verbal and nonverbal cognitive abilities. Two diagnoses were utilized: strict autism and ASD. Children with autism or ASD that was included in the initial data and confirmed by the researchers were considered "probands."

The final analysis included 54 pairs of identical twins and 138 pairs of fraternal twins (of which 80 were composed of a boy and a girl). Researchers found the likelihood of both children having autism or ASD was higher among identical twins than among fraternal twins. They also used modeling to estimate how much of the risk could be attributed to genetic factors. This analysis demonstrated that more than half of the variance in risk was probably explained by shared environmental factors, versus less than 40 percent of the risk owing to genetic heritability.

"The results suggest that environmental factors common to twins explain about 55 percent of the liability to autism," the authors write. "Although genetic factors also play an important role, they are of substantially lower magnitude than estimates from prior twin studies of autism. … The finding of significant influence of the shared environment, experiences that are common to both twin individuals, may be important for future research paradigms."


Story Source:

The above story is based on materials provided by JAMA and Archives Journals. Note: Materials may be edited for content and length.


Journal Reference:

  1. Joachim Hallmayer; Sue Cleveland; Andrea Torres; Jennifer Phillips; Brianne Cohen; Tiffany Torigoe; Janet Miller; Angie Fedele; Jack Collins; Karen Smith; Linda Lotspeich; Lisa A. Croen; Sally Ozonoff; Clara Lajonchere; Judith K. Grether; Neil Risch. Genetic Heritability and Shared Environmental Factors Among Twin Pairs With Autism. Archives of General Psychiatry, 2011; DOI: 10.1001/archgenpsychiatry.2011.76

Cite This Page:

JAMA and Archives Journals. "Genetic component of autism spectrum disorders may be moderate compared to environment, twin study suggests." ScienceDaily. ScienceDaily, 4 July 2011. <www.sciencedaily.com/releases/2011/07/110704174616.htm>.
JAMA and Archives Journals. (2011, July 4). Genetic component of autism spectrum disorders may be moderate compared to environment, twin study suggests. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2011/07/110704174616.htm
JAMA and Archives Journals. "Genetic component of autism spectrum disorders may be moderate compared to environment, twin study suggests." ScienceDaily. www.sciencedaily.com/releases/2011/07/110704174616.htm (accessed October 2, 2014).

Share This



More Mind & Brain News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pregnancy Spacing Could Have Big Impact On Autism Risks

Pregnancy Spacing Could Have Big Impact On Autism Risks

Newsy (Oct. 1, 2014) A new study says children born less than one year and more than five years after a sibling can have an increased risk for autism. Video provided by Newsy
Powered by NewsLook.com
Stopping School Violence

Stopping School Violence

Ivanhoe (Oct. 1, 2014) A trauma doctor steps out of the hospital and into the classroom to teach kids how to calmly solve conflicts, avoiding a trip to the ER. Video provided by Ivanhoe
Powered by NewsLook.com
Pineal Cysts: Debilitating Pain

Pineal Cysts: Debilitating Pain

Ivanhoe (Oct. 1, 2014) A tiny cyst in the brain that can cause debilitating symptoms like chronic headaches and insomnia, and the doctor who performs the delicate surgery to remove them. Video provided by Ivanhoe
Powered by NewsLook.com
Burning Away Brain Tumors

Burning Away Brain Tumors

Ivanhoe (Oct. 1, 2014) Doctors are 'cooking' brain tumors. Hear how this new laser-heat procedure cuts down on recovery time. Video provided by Ivanhoe
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