Can Autism be Inherited? 5 Myths about Autism Genetics

‍Myth - There is No Genetic Cause for Autism

Reality: Autism spectrum disorder (ASD) is considered a complex neurodevelopmental genetic condition most frequently suspected in children. In families with existing cases of ASD, similar traits and patterns often appear. These findings suggest that although there is not one single gene that causes all of autism, genetics has a large influence on its development. It’s also true that 20-30% of individuals with an Autism Spectrum Disorder can be attributed to an identifiable genetic cause. In the remaining 70-80% of individuals with an ASD for which an underlying genetic cause cannot be identified, the cause is considered to be multifactorial^1-4. Multifactorial means a combination of multiple genetic and environmental factors that contribute together. Other risk factors include advanced paternal age at conception, certain prenatal exposures, maternal health conditions in pregnancy, prematurity or low birth weight, and difficult births resulting in lack of oxygen⁵. It's important to note that none of these conditions on their own is likely to cause autism, they appear to be risk factors when combined with other genetic factors.

Read more about the causes of autism here and the difference between monogenic and polygenic conditions here.

Myth - If Parents Have a Child with Autism, Their Next Child Will Definitely Have It

Reality: The chance for a child to have autism based on a family history is very dependent on the type and severity of autism in the family. For example, if a child is known to have an autosomal recessive monogenic form of autism, the risk for future children can be as high as 25%. However, if the autism in the family is considered multifactorial, the recurrence risk is much more variable and dependent on a variety of different factors. This 2011 study estimated that 18.7% of children with at least one older sibling with ASD also were diagnosed - the two biggest factors were the number of affected siblings and the biological sex of the children⁶. Learn more about how family history influences risks here.

Because the genetics of autism is complex, information concerning the diagnosis of family members is very important in assessing the risk to future children. In fact, the American Academy of Pediatrics and the American College of Medical Genetics both recommend genetic testing for any child suspected of an autism spectrum disorder (ASD). Discussing your family history with a comprehensive genetic counselor is a great first step to learning about your family’s recurrence risk - find one in your area here.

Myth - No One in My Family Has Autism, So There is No Risk to My Children

Reality: Regardless of your family history, anyone has a chance of having a child affected with a genetic form of autism (ASD). This means a child can develop autism even if there is no prior family history. This is because a large proportion of genetic Autism Spectrum Disorders (ASD) happen by chance in an individual. These “de novo” mutations are only in an individual’s DNA, and are not likely to be inherited⁷.

Myth - Genetic Testing Can Diagnose Autism

Reality: Autism itself is a behavioral diagnosis, but it is often seen as part of a heritable condition. Genetic testing, therefore, should not be the only tool confirming this diagnosis. Genetic testing can be useful in identifying mutations that cause symptoms of autism (e.g., conditions like Fragile X Syndrome and Rett syndrome). ASD is more likely to be genetic if it is severe and/or syndromic. Autism spectrum disorders’ severity reflects the average contribution of de novo and familial influences.

Learn more about the genetic testing for autism here.

Myth: There is No Way to Screen for Autism Prior to Conception

While there is no way to diagnose an embryo with autism since it is a behavioral diagnosis, Orchid’s PGT-WGS is the first embryo screening to include over 200 genes associated with monogenic forms of neurodevelopmental disorders, such as autism.

Benefits of this screening:

Available to all individuals undergoing IVF
Can detect de novo mutations previously unidentifiable before birth
Provides additional risk reduction beyond traditional embryo screening methods

Important considerations:

Because not all cases of autism are genetic, genetic screening can not eliminate the risk of autism
Orchid’s evaluation can only reduce risks for the forms of autism included on this screening
If you have a family history of autism that doesn’t have a known genetic cause, risks are still expected to be elevated

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If you have a known genetic cause of autism in your family and want to explore embryo screening options, Orchid's board-certified genetic counselors are available to help determine if our screening technology might be beneficial in your specific case. Contact us at genetics@orchidhealth.com for more information.

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References:

Miller, D. T., Adam, M. P., Aradhya, S., Biesecker, L. G., Brothman, A. R., Carter, N. P., Church, D. M., Crolla, J. A., Eichler, E. E., Epstein, C. J., Faucett, W. A., Feuk, L., Friedman, J. M., Hamosh, A., Jackson, L., Kaminsky, E. B., Kok, K., Krantz, I. D., Kuhn, R. M., Lee, C., … Ledbetter, D. H. (2010). Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. American journal of human genetics, 86(5), 749–764. https://doi.org/10.1016/j.ajhg.2010.04.006
Schaefer, G. B., & Mendelsohn, N. J. (2008). Genetics evaluation for the etiologic diagnosis of autism spectrum disorders. Genetics in medicine : official journal of the American College of Medical Genetics, 10(1), 4–12. https://doi.org/10.1097/GIM.0b013e31815efdd7
Schaefer, G. B., Mendelsohn, N. J., & Professional Practice and Guidelines Committee (2013). Clinical genetics evaluation in identifying the etiology of autism spectrum disorders: 2013 guideline revisions. Genetics in medicine : official journal of the American College of Medical Genetics, 15(5), 399–407. https://doi.org/10.1038/gim.2013.32
Woodbury-Smith, M., & Scherer, S. W. (2018). Progress in the genetics of autism spectrum disorder. Developmental medicine and child neurology, 60(5), 445–451. https://doi.org/10.1111/dmcn.13717
https://www.niehs.nih.gov/health/topics/conditions/autism
Ozonoff S, Young GS, Carter A, Messinger D, Yirmiya N, Zwaigenbaum L, Bryson S, Carver LJ, Constantino JN, Dobkins K, Hutman T, Iverson JM, Landa R, Rogers SJ, Sigman M, Stone WL. Recurrence risk for autism spectrum disorders: a Baby Siblings Research Consortium study. Pediatrics. 2011 Sep;128(3):e488-95. doi: 10.1542/peds.2010-2825. Epub 2011 Aug 15. PMID: 21844053; PMCID: PMC3164092.
Yoon et. al. Rates of contributory de novo mutation in high and low-risk autism families. Commun. Biol. 2021; 4: 1026. PMID: 34471188

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