Autism and Genetics: What are the Odds?

The diagnosis of autism spectrum disorder (ASD) is more than just a label. The diagnosis not only impacts the individual but the entire family. After receiving a diagnosis of autism, questions may include – Why? What do we do next? How will this impact my child, me, my family? Where did this come from? What caused this? For many of these questions we don’t have a good or straightforward answer. What we do know is that autism is complex.

Newer genetic testing platforms and other technologies have brought an increased focus on understanding the causes of autism. In general, autism is thought to be caused by a combination of both genetic and environmental factors. Earlier this year a study published by JAMA Psychiatry looked at how these factors play a role in autism (1). In this new study it was revealed that about 80% of autism is heritable.

This means about 80% of autism is caused by genetic factors. For most, there it is not a single genetic factor, rather a combination of multiple factors. This also means, for most, there is not a simple test that can be done to identify the cause.  

However, for about 20-40% of those with autism, there is an identifiable underlying genetic cause. This may include chromosome abnormalities or single gene disorders.  For this reason, multiple organizations have recommended that all individuals with a diagnosis of autism be referred for genetic testing (2). Genetic testing may involve chromosome analysis, chromosome microarray, single gene testing, multigene panel testing, or other. Identification of a genetic cause may provide more information about whether someone is at risk for other potential health problems.

So, who should undergo genetic testing?  Anyone with a personal or family history of autism may wish to speak with a genetic professional. Evaluation involves a detailed review of personal and family medical history. This review determines whether genetic testing is indicated, and if so, what is the most appropriate test.  

With all of this information, you may ask – what will this information do for me? for my child? for my family? For some, undergoing genetic testing may cause more uncertainty and bring up more questions, some of which we will not have answers. For others, undergoing genetic testing may help them better understand the diagnosis and any future health implications. In the end, the decision is up to the individual, to the family.

If interested in receiving more information you can schedule with one of our board-certified genetic counselors.


(1) Bai D, Yip BHK, Windham GC, et al (2019). Association of Genetic and Environmental Factors With Autism in a 5-Country Cohort. JAMA Psychiatry. Published online July 17, 2019, 76(10):1035–1043. doi:10.1001/jamapsychiatry.2019.1411

(2) American College of Medical Genetics, American Academy of Neurology, American Academy of Pediatrics, American Academy of Child and Adolescent Psychiatry, International Standard Cytogenomic Array Consortium