How genetic is autism?

How genetic is autism?

According to a new study published by JAMA Pediatrics, children with older siblings who have been diagnosed with autism are seven times more likely than other children to have the disorder themselves.

Autism spectrum disorders (ASDs) are a range of developmental neurological disorders which are linked to social impairment and communication difficulties. They include classic autism, Asperger syndrome, Rett syndrome, pervasive developmental disorder – not otherwise specified (PDD-NOS) and childhood disintegrative disorder. According to the Center for Disease Control, one in every 88 children has an ASD.

The study, which was conducted by Aarhus University in Denmark, tracked the birth and psychiatric registries of 1.5 million Danish children born between 1980 and 2004 and the rate of autism among the surveyed population through 2010.

The researchers found that of the 130,000 children born during that time with an ASD, nearly 300 had an older sibling with the same disorder. Statistically, these younger siblings of children on the autism spectrum were found to be about seven times more likely than other children to be on the autism spectrum themselves.

In addition, children who shared the same mother with an autistic older half-sibling were found 2.4 times more likely than other children to place on the spectrum.

“This study reports siblings diagnosed with an autism spectrum disorder, at a slightly lower rate than reported in past studies,” notes Laura Mulford, PhD, a child psychologist at the Pediatric Developmental Center at Advocate Illinois Masonic Medical Center in Chicago. “Autism spectrum disorders are complex neurological disorders and we’ve known for some time that there is a genetic piece involved, but this estimate is somewhat more conservative than we’ve seen in the past.”

An exact gene that is responsible for autism spectrum disorders has not yet been identified; however, experts at the National Institute of Neurological Disorders and Stroke (NINDS) are in agreement that genetics are at work.

Environmental factors, such as increased parental awareness of the symptoms of autism with one child already diagnosed, may also play a role in these shared sibling diagnoses, according to the NINDS.

“Often families ask about the risk of having another child diagnosed with an autism spectrum disorder, and general figures such as this one are useful pieces of information for families to have,” Dr. Mulford adds. “But keep in mind that this figure does tend to slightly fluctuate and overall while there is an increased risk due to family history, there are several factors that influence whether or not another child would have an autism spectrum disorder.”

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  1. Let’s not push the Autism is genetic bit or make the disorder sound comfortably acceptable. Ask yourself why 1 in 50 children are being diagnosed with Autism when it used to be much much more rare. It’s the environment humans have created most likely from the over abundance of vaccinations given to children. The # of vaccines with toxic ingredients have greatly increase over the years and there are many links to autism. Let’s solve the problem, there is no gene because toxins in the vaccines are causing cells to be compromised.

  2. Nothing has linked vaccines to ASD. There are other environmental factors at work though. The food women eat while pregnant, the food we feed our young children has changed so much over the last 50 years. There are many antecdotal cases in which a child’s behavior has been positively effected by a change in diet. People view ASD as a “bad thing” and while we don’t want our children to always be dependent on others it is important to understand that it’s not “bad” just a different way of viewing the world.

  3. Actually, there is a lot which links vaccines to autism. Vaccines are the Big Tobacco of our age in the US alone 33 BILLION a year. In amny cases, independent research has been discounted and even unjustly attacked because of the links it has found. There is everything from toxins to human DNA – due to the use of electively aborted fetuses in development, that is a fact which can be looked up and is specifically linked to MERCK company — MMR, Varivax, Zostavax, Rabies vaccine etc – it is listed as dipliod cells on the package insert. It seems that anyone who looks at the anecdotal evidence of the individual introduction of certain vaccines and the 1 year to 2 year correspondence in the rise of autism then reported is labeled a freak, “religious” fanatic or just another dumb scientist.

  4. Dr. Lisa Yeh
    Lisa C. Yeh, M.D. August 26, 2013 at 3:02 pm · Reply

    It is unfortunate that the fraudulent research by Andrew Wakefield continues to fuel erroneous belief that there is a link between vaccinations and Autism. Since his now discredited research was first published in 1998, there are numerous studies that have not found any link of vaccinations to Autism. Even attempts to replicate Andrew Wakefield’s research did not show any link between vaccinations and Autism. Autism is a complex neurological disorder that symptoms commonly are noticed around 18 months which is around the time of some vaccinations. However, research has shown that the rate of Autism remains the same with or without the vaccinations. The correlation between timing of Autism and of vaccinations does not prove causation. There is no credible research that shows a link between vaccinations and Autism. A list of research can be found on the CDC website at

    Research does show genetics and other environmental factors are involved in Autism. Autism is a very complex disorder and is seen to span the genome with multiple small errors in the genome together presenting as Autism. It is not a simple one gene answer. The dramatic increased reporting of Autism does not mean there is an equally dramatic increased rate. There are a number of factors that go into the increased reporting. These factors include such things as change in the criteria and awareness. Awareness is a very large factor due to the increase of children being referred who would have previously never been referred for evaluation. Doctors, teachers and parents more readily refer children for evaluation. Also, Autism is associated with many other genetic illnesses and with intellectual disability. Previously, children initially seen for the genetic illnesses or intellectual disability would not have had been evaluated for Autism once the genetic illness was diagnosed. These children may have also had Autism but were not identified. For instance, a large percentage of children with Autism have intellectual disability. As the rate of reporting of Autism has increased, the rate of intellectual disability has decreased. This is not to say there is a smaller percentage of children with intellectual disability but that often now once a child is diagnosed with Autism the diagnosis of intellectual disability is not given.

    Vaccinations are an extremely important part in maintaining the health of children. Illnesses such as mumps, measles, rubella, etc. can have very serious sequelae if young children catch these illnesses. This includes causing motor and speech delays, intellectual disability, coma and death. The decrease in vaccinations has caused a significant rise in very serious illnesses in children and a rise in deaths that could have been prevented. Thousands of children have already died and even more have debilitating consequences of these illnesses. Currently in the United States we have some amount of herd immunity which means that most people are vaccinated and protected and this protects unvaccinated children as long as the illnesses are kept to a very limited amount. However, if children continue to not get vaccinations herd immunity will no longer protect them. This means that the number will exponentially increase if children do not get immunizations. Most at risk will be infant that are too young to have a full set of vaccinations. I have been treating children with disabilities and with Autism for over 20 years now and have extensively reviewed Autism research. I would never recommend something that I felt was dangerous or would cause Autism. Vaccinations are a necessary part of good healthcare. It is important to know there is no link between vaccinations and Autism. If parents have concerns about vaccination they can look at the CDC website for information about vaccinations at

    Lisa C. Yeh, M.D.
    Attending Child/Adolescent Psychiatrist
    Advocate IL Masonic Hospital,
    AMG Pediatric Developmental Center

    Hummm? I still question this. I have 2 grandchildren under the age of 4 with PDD NOS & they were both normal before their shots. I’m sorry….. my daughter is a nurse & my mother in law is a pharmacist. I have done a lot of research on this trust me!

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health enews Staff
health enews Staff

health enews staff is a group of experienced writers from our Advocate Health Care and Aurora Health Care sites, which also includes freelance or intern writers.