Scientists from the University of California Los Angeles (UCLA), Stanford University, and the California Institute of Technology report that they used genome sequencing to identify 69 genes that increase the risk of autism spectrum disorder.
“That’s a pretty significant finding, and for anyone who has one of those particular genes it’s going to be even more significant,” Dr. Daniel Geschwind, senior author of the study and a professor of human genetics, neurology, and psychiatry at UCLA, told Healthline.
“These genetic mutations you should think of as causes of autism. They are contributing to the likelihood of that child having autism. We anticipate that there might be up to 1,000 genes that might be mutated in autism,” he said.
The researchers mapped the DNA of 2,300 people from nearly 500 families who had at least two children with autism.
Among the 69 genes identified as increasing the risk of autism, 16 were not previously thought to be associated with autism.
The study included participants with autism and participants without the disorder. This helped researchers examine the differences in genetics of children with and without autism in different families.
This research is the latest piece of the puzzle in uncovering the causes behind autism and, researchers hope, developing targeted therapies for the condition.
“By identifying these different forms of autism, they provide a true and clear road to developing a targeted therapy. You know now what the mutation is, what gene it affects — you can figure out what cells that gene is expressed in and when, you can figure out how that mutation then leads to abnormalities in development, and you can work out how to treat that specifically,” Geschwind said.
The ABCs of autism
Autism spectrum disorder is a developmental disorder affecting 1 in 59Trusted Source children in the United States.
Boys are four times more likely to be diagnosed with autism than girls.
Autism encompasses a variety of conditions that can cause repetitive behavior and problems with social skills and communication.
Those with autism may have a delay in learning language, trouble holding a conversation and making eye contact, trouble with motor skills or sensory activity, and narrow or intense interests in certain topics.
Researchers say there’s no single cause of autism, but rather it’s likely a combination of genetic and environmental factors.
“We have a pretty good idea that around 70 to 80 percent of the risk for autism is inherited or other genetic factors. It leaves some room for environmental effects and there are definitely known environmental causes of autism as well,” Geschwind said.
Prenatal exposure to chemicals such as valproic acid and thalidomide has been linked to a heightened risk of autism, but experts says it can be hard to pinpoint environmental factors.
“It is very difficult to document what a mother, fetus, or child has been exposed to during their early years of life,” Dean M. Hartley, PhD, senior director of genomic discovery and translational science at Autism Speaks, told Healthline.
“These studies are expensive and time consuming and will require much greater federal funding to carry out these important studies,” Hartley adds.
He says that past incorrect claims about what causes autism are still doing damage. “The most pronounced damaging claim is that vaccination causes autism. There are no credible studies to point to this claim and those valid, large-scale studies have shown no association.”
“Unfortunately, because of the lack of vaccinations, people are at greater risk for developing serious communicable disease, as recently seen with the increase of measles cases. There is a lot of misinformation being spread,” he said.
Early diagnosis is important
Identifying symptoms of autism early is important for improving outcomes for children.
Not all children with autism will show all signs, and some may not display obvious behaviors until age 2 or 3.
Experts say things to look out for include:
- a lack of smiling
- limited eye contact
- little or no response to name
- a preference for solitude
- delayed language development
- intense reactions to sound, smell, taste, lights, or colors
Researchers are hopeful that identifying genes that increase risks of autism will assist in early diagnosis.
“There is strong evidence suggesting that early intervention leads to improved outcomes for many children with autism. If we are able to perform genetic screens to identify if children are at higher risk, this would allow us to intervene immediately rather than wait until features begin to show up later in childhood,” Megan Dennis, PhD, an assistant professor in the department of biochemistry and molecular medicine at the University of California Davis, told Healthline.
“Also, understanding mechanisms may help to alleviate other co-occurring symptoms such as sleep problems and gastrointestinal disturbances through changing diet or medication targeting those pathways,” she added.
The need for research
Autism is a complex disorder with a variety of symptoms. Researchers argue the variety of symptoms and variance in severity suggests there are likely multiple subtypes and causes.
Hartley argues that in order to identify more causes of autism, larger studies are needed.
“We need more genetic studies with much larger numbers of participants,” he said.
“Because of the large behavioral spectrum of autism, it is thought that hundreds of genes may be involved, but only some subset of genes is probably involved in any single person with autism. To detect these subgroups we will need much larger numbers than we currently have,” he continued. “This will require a larger commitment of federal dollars for research.”
Geschwind and his colleagues are hopeful that their research will enable better treatment options and improved outcomes for children diagnosed with autism.
“The hope is… with genetics and other biomarker measurements we have, we will be able to capture children early, have a sense of what the best treatment is for that particular child, optimize their outcomes, and be able to share that with parents at the earliest possible stages so as to eliminate or to reduce the incredible uncertainty that comes with a diagnosis like this,” he said.
He emphasizes that the goal isn’t necessarily to eliminate autism entirely but to improve outcomes for people with the disorder and their families.
“Individual differences should be hugely celebrated and to the extent that somebody with autism is… happy with their functioning… and everything is going well for them as far as they’re concerned, that’s great and that’s the last sort of person whose life you would want to interfere with,” Geschwind said.
“On the other hand, we interact with a lot of parents whose kids are very severely disabled, who don’t speak, who can’t go to school, who don’t have friends, who have intractable seizures and other medical problems, and those are the cases we’re most interested in trying to help,” .