Skip 
Navigation Link
Autism
Resources
Basic InformationMore InformationLatest News
Maternal Multivitamin Use Tied to Lower Risk of Child ASDResearchers Learn More About Gender's Role in Autism RiskGenetics a Cause of Autism in Most Cases: StudyCould Folic Acid Fight a Cause of Autism?Does Autism Risk Reside in Cells' Energy Engines?Therapy for Kids With Autism Pays Off for Moms, DadsCan Scans Predict Some Autism Cases?Guidelines Developed for Art Therapy for Children With ASDAntidepressants in Pregnancy Tied to Slight Increase in AutismCan a Spritz of 'Love Hormone' Help Kids With Autism?Why People With Autism Avoid Eye ContactWhen is Tourette Syndrome Actually Autism?Study Cites Top Reasons Young Autism Patients Are HospitalizedFever During Pregnancy Tied to Autism in StudySpecial Brain Scans May Predict Autism in High-Risk BabiesBaby Teeth Study Points to Links Between Autism, Lead LevelsCommunication Problems Not at Root of Tantrums in Kids With AutismNo Proof Special Diets, Supplements Work for AutismCould a Century-Old Drug Help Ease Autism Symptoms?Autism's 'Worryingly' High Suicide Rates Spur ConferenceSpecial Diets, Supplements for Autism Still a Question MarkProdromal Intervention Effective for Infants at Risk of AutismProgram Helps Young Adults With Autism Find JobsTreat Autism Even Before Symptoms Show?Tracking Devices May Ease Minds of Parents of Kids With AutismYoung Adults With Autism Need Help Managing Money: StudyFDA Warns Against Bogus Autism 'Cures'1 in 3 Teens With Autism Licensed to Drive, Study Finds'Video Feedback' Program Might Help Treat Autism in BabiesMuppet With Autism Makes Her 'Sesame Street' DebutParents of Kids With Autism May Sacrifice 'Couples Time'Teens With Autism More Likely to Land in ER, Study FindsHigher Risk of Death From Injury Among Individuals With AutismAutism Greatly Boosts Kids' Injury Risk, Especially for DrowningCould a Blood Test Spot Autism in Childhood?MRI Can Identify Early Signs of ASD in High-Risk InfantsExperimental Test Can Spot Autism in InfancyBrain Differences Hint at Why Autism Is More Common in MalesU.S. Legislation Boosted Access to Autism Services, With No Added Cost to FamiliesObstetric Complications Tied to Slightly Upped Risk for AutismMicrobiota Transfer Therapy Could Help Children With AutismFecal Transplant Shows Early Promise Against AutismStress May Explain Digestive Issues in Kids With AutismNo Link for Maternal Flu Infection, Increased ASD RiskParent-Led Autism Therapy Shows Lasting BenefitsGuideline Changes Have Asperger's Community on Edge
Questions and AnswersLinksBook Reviews
Related Topics

Childhood Mental Disorders and Illnesses
Parenting

Genetics a Cause of Autism in Most Cases: Study

HealthDay News
by By Randy Dotinga
HealthDay Reporter
Updated: Sep 26th 2017

new article illustration

TUESDAY, Sept. 26, 2017 (HealthDay News) -- Heredity contributes to about 83 percent of the risk of autism in children with the disorder, a new study suggests.

The estimate, from a re-analysis of a previous study, adds a new wrinkle to the ongoing debate over how much autism is inherited from parents. Essentially, the findings suggest that rare genetic traits combine in parents and explain about eight in 10 cases of the neurodevelopmental disorder in children.

However, study author Sven Sandin cautioned that "our results do not give any information about specific genes or other direct causes. It only informs us that genes are important."

Sandin, an assistant professor of psychiatry at the Icahn School of Medicine at Mount Sinai in New York City, noted that the findings also don't reflect anything about the reported increases in autism rates in recent years. The higher rates must have something to do with increased awareness or environmental factors, "and our study cannot shed any light on this," he said.

Previous research had estimated the heritability of autism as anywhere from more than 50 percent to as much as 90 percent, said Dr. Dan Geschwind, a geneticist who's familiar with the findings.

"We already know that autism has very substantial genetic contributions," said Geschwind, chair in human genetics at the University of California, Los Angeles School of Medicine. "The question is how much is genetic and how much is environmental?"

For the new study, researchers re-analyzed statistics from a previous study that tracked children born in Sweden between 1982 and 2006. The children were followed through 2009 to see if they developed autism spectrum disorders. The goal was to determine how common the disorders are in various types of siblings (such as twins), which would indicate the importance of genetics.

In total, the study looked at 37,570 pairs of twins, 2.6 million pairs of siblings, and nearly 888,000 pairs of half-siblings. Of all these, just over 14,500 children were diagnosed with autism spectrum disorders. The new study did not report the races of the children.

While the researchers estimated that inherited factors contribute to 83 percent of the risk, "even in couples who already have a child with autism, the likelihood that their next child will also develop autism is increased, but still not very high," Sandin said.

Still, Sandin noted, the heritability of autism appears to be higher than some psychiatric conditions. For example, "the heritability of schizophrenia has been estimated to be 80 percent, and for attention-deficit/hyperactivity disorder it has been estimated at 76 percent," he said.

"For cancer, it is very different for different types and for when they occur in life. For skin melanoma and prostate cancer, respectively, the heritability was recently estimated to 57 percent and 58 percent," Sandin said.

Geschwind noted that the study is large, which supports the validity of the findings. "At some level, it is important to show that it's heritable," he said. "But this finding won't really change the kind of work that most geneticists do."

In the United States, an estimated one in 68 school-aged children has an autism spectrum disorder, according to an estimate from the U.S. Centers for Disease Control and Prevention. Symptoms include difficulty communicating and interacting with others, and a tendency toward repetitive behaviors and obsessions.

The new study was published Sept. 26 in the Journal of the American Medical Association.

More information

For more about autism, visit the U.S. Centers for Disease Control and Prevention.