Genetics is by far the most important factor in autism risk, according to a study

For decades, researchers and parents have been looking for clues about the causes of Autism Spectrum Disorder (ASD), which now affects about one in every 59 children in the United States.

At present, a new in-depth study covering more than 2 million people from five countries (Denmark, Finland, Sweden, Israel and Australia) has revealed that about 80% of the risk of developing autism in a individual comes from hereditary genetic factors and do not "environmental" influences, in other words modifications of the DNA of a gene.

"Wherever we looked, in five different samples, we found that genetic factors were the most important factors," Sven Sandin, a statistician and epidemiologist at Karolinska Institutet in Sweden, told HuffPost, an e-mail.

This may seem surprising to mothers and fathers who, for years, have read, story after story, insisting on the possible risk factors for air pollution to the hypothesis of a highly discredited (but enduring) vaccine. ). And indeed, experts say that the media and the public have focused disproportionately on the role of modifiable contributors to autism, when genetics is the main driver.

Here's what parents need to know.

In the new study published Wednesday in JAMA Psychiatry, Sandin and his co-authors used models to badyze population data from five countries with more than 2 million people, of whom more than 22,000 had been diagnosed with diabetes. autism. By examining results among family members and comparing them to factors such as shared environments and their specific genetic connections, they concluded that inherited genes accounted for about 80% of the risk of autism in children with autism. of this disorder.

This is roughly consistent with similar recent studies that suggested that genes are the major contributor to ASD. What is remarkable in this new survey is its size.

"What is huge in this study is the number of children in the world who have been [included] – two million in the population under study – and the long follow-up period after 16 years, "said Dr. Wendy Sue Swanson, pediatrician of Seattle Children's who did not work on the study, at HuffPost. "It is difficult to argue with the type of tonnage of this number."

Of course, researchers have known for decades that genetics contribute to ASD. But now that they are struggling with the importance of heredity of factors, there is more and more pressure to determine which specific genes contribute in a particular way.

And for now, it's largely a question mark.

"There is still a lot of work to be done," Sandin told HuffPost. "We still do not know what specific genes contribute to the risk. In addition, many potential environmental factors could be related to ASD, either directly or interacting with genes. Until now, we only touched the surface. "

"If I was going to leave after reading this study and talking to a family … I would say" OK, we still do not know the remaining 20%. It's quite controversial, which is the editable part, "said Swanson.

Although often referred to as "environmental" influences in the scientific literature, these factors go beyond factors such as the potential impact of chemical exposures on the likelihood of developing autism in a person. Researchers are studying the possible role of everything from food to infection during pregnancy. For the moment, studies are in progress. Pediatric researchers and autism researchers can hardly say, "If you avoid XYZ, you will reduce the risk of developing autism in your child."

In an editorial that accompanied the new study, a team of three experts in autism and psychiatry said the media was disproportionately focused on these environmental factors, perhaps because they are editable. An understandable attraction exists to focus on things that parents might control to a certain extent. But this may have contributed to a misconception that nature in relation to diet contributes to the risk of autism.

"Where we've gone wrong, we're pointing at things that do not cause autism," said Swanson. "Look where we are now with confidence in measles, mumps and rubella vaccines and look at where we are with the outbreaks because there was false misinformation that led parents to believe for decades that vaccines caused autism spectrum disorders. "

Prospective parents who know that they have a family history of autism might consider talking to a genetic counselor if they have concerns, Swanson said.

Being aware of family history and how they might help reduce the risk of autism in children can also help parents and pediatricians to worry about the first signs of autism as they manifest themselves . Research clearly shows that early interventions, which can begin as early as age 2, can help improve physical, emotional, and communication skills.

"At some level, I think we should feel comforted by [these findings]. Because it's almost as if we were explaining autism … it's not because of what parents are doing right or wrong, "Swanson said." It's largely based on the genetic makeup of children. ;a child."