My brother has autism, what does this mean for me?

My brother has autism, what does this mean for me?

An overview of what a sibling's autism diagnosis can mean for you and your children.

Written by Maria Katz, MS, CGC, Reviewed by Xiaoli Du, PhD, FACMG, DABMGG, CGC,CGMBS

Dr. Du is an American Board of Medical Genetics and Genomics (ABMGG) certified geneticist. With a passion for precision medicine, she leverages cutting-edge molecular genetics and cytogenetics technology to improve outcomes for individuals affected by genetic conditions. Dr. Du has nine years of clinical genetic diagnosis experience in both the public and private sectors.

My brother has autism, what does this mean for me?

Having a family member with an Autism Spectrum Disorder can increase your chances of having a child with Autism4. Whether a sibling, cousin or other family member has a clinical diagnosis of an Autism Spectrum Disorder, the most important information in regards to your own chance to have a child with an Autism Spectrum Disorder is information on their diagnosis. 

The reason why information on family members is important is because the genetics of autism is complex. It is well established that genetics can contribute to Autism Spectrum Disorders. However, only 20-30% of individuals with an Autism Spectrum Disorder can be attributed to an underlying genetic cause. In the remaining individuals with an Autism Spectrum Disorder for which an underlying genetic cause cannot be identified, the cause is considered to be multifactorial6-9. Multifactorial means a combination of multiple genetic and environmental factors that contribute together.

My family member with autism has not had genetic testing

First and foremost, identifying a cause in a family member is the most effective way of quantifying the chance your future child has of developing an Autism Spectrum Disorders . Individuals with a clinical diagnosis of an Autism Spectrum Disorder are recommended to meet with a geneticist and discuss testing options, including Fragile X testing and a chromosome microarray to evaluate copy number variants (extra or missing pieces of chromosomes). More extensive testing would be recommended for some individuals, including larger gene panels, whole exome or whole genome sequencing8

My family member has a known genetic cause for their autism spectrum disorder.

Genetic changes can happen in two ways: they can be inherited from a parent or happen by chance in an individual (called "de novo"). Knowing what kind of genetic change caused the Autism Spectrum Disorder in your family can help you know if your future children are more likely to have an Autism Spectrum Disorder compared to other people. No matter what your family history is, everyone has a chance of having a child with an Autism Spectrum Disorder.

A few examples:

Fragile X syndrome2

  • Individuals with Fragile X syndrome have characteristic facial features, varying levels of developmental delay, learning disability and/or an Autism Spectrum Disorder. 
  • Individuals with Fragile X syndrome typically inherit the condition from an unaffected biologically female parent. 
  • If you have a family history of Fragile X Syndrome, recurrence chances would depend on your genetics, including carrier status and biological sex.


Neurofibromatosis Type 13

  • Neurofibromatosis Type 1 (NF1) is a single-gene disorder which means that a change in one gene causes a condition. NF1 is characterized by distinctive skin pigmentations and tumor growths. Over 20% of individuals with NF1 also have an Autism Spectrum Disorder. 
  • Individuals with NF1 may have an affected parent, but ~50% of individuals with NF1 are the first in their family (meaning it occurred de novo in them).
  • If you have a family history of NF1, recurrence chances would depend on your own genetics. If you have NF1 yourself, your offspring would have a 50% chance of having NF1 as well. 

My family member with autism has had negative genetic testing

If your family member has had appropriate, negative genetic testing and has an Autism Spectrum Disorder with no other clinical features (for example an intellectual disability or a birth defect), their autism would be considered multifactorial. Multifactorial means that a combination of multiple genetic and environmental factors contribute together causing the Autism Spectrum Disorder. Having a family member with an Autism Spectrum Disorder can increase your chances of having a child with Autism. Studies have demonstrated that autism is highly heritable, with studies estimating a range of 50-80% (see this Orchid Guide for more)4. The chance for your offspring to also have an Autism Spectrum Disorder, would depend on how closely related the family member is and their biological sex.

Based on my family history of autism, are there options for me to prevent or reduce the chance of having a child affected with autism?

If you have a known genetic cause for an Autism Spectrum Disorder  in your family, genetic testing may be recommended for yourself:

  • In the example above, if you have a family history of Fragile X syndrome and you are biologically female, carrier screening for Fragile X syndrome would be recommended. 

If you have a known genetic cause for an Autism Spectrum Disorder in your family, embryo screening is available:

  • Through embryo screening, Orchid can help you select embryos that did not inherit the genetic cause for Autism seen in your family.
  • Please share this information with Orchid prior to embryo screening.

Regardless of your family history, anyone has a chance of having a child affected with a genetic Autism Spectrum Disorder. This is because a large proportion of genetic Autism Spectrum Disorders happen by chance in an individual (called "de novo")10.

Embryo screening is available:

  • Orchid offers a neurodevelopmental panel that can reduce the chances of inherited and non-inherited (de novo) genetic changes known to cause Autism Spectrum Disorders and other neurodevelopmental disorders. 
  • The genes included on this panel were created by a group of experts in the field of genetics (clinical domain group) as being linked to Autism Spectrum Disorders and other neurodevelopmental disorders1.
  • As a reminder, no one test can detect all possible genetic causes of Autism Spectrum Disorder, and not all Autism Spectrum Disorder cases are caused by a change in a single gene.

You may or may not be concerned about your family history of an Autism Spectrum Disorder, but if you have any questions about your family history of the genetics of autism, it is always recommended to review your family history with a genetic counselor. 

References
  1. Clinical Domain Working Groups. Intellectual Disability and Autism Gene Curation Expert Panel. Retrieved from: https://www.clinicalgenome.org/affiliation/40006/
  2. Hunter JE, Berry-Kravis E, Hipp H, and Todd,P.  (1998, updated: 2019). FMR1 Disorders. 1GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1384/
  3. Garg, S., Green, J., Leadbitter, K., Emsley, R., Lehtonen, A., Evans, D. G., & Huson, S. M. (2013). Neurofibromatosis type 1 and autism spectrum disorder. Pediatrics, 132(6), e1642–e1648. https://doi.org/10.1542/peds.2013-1868
  4. Larsen, E., Menashe, I., Ziats, M. N., Pereanu, W., Packer, A., & Banerjee-Basu, S. (2016). A systematic variant annotation approach for ranking genes associated with autism spectrum disorders. Molecular autism, 7, 44. https://doi.org/10.1186/s13229-016-0103-y
  5. Lichtenstein, P., Carlström, E., Råstam, M., Gillberg, C., & Anckarsäter, H. (2010). The genetics of autism spectrum disorders and related neuropsychiatric disorders in childhood. The American journal of psychiatry, 167(11), 1357–1363. https://doi.org/10.1176/appi.ajp.2010.10020223.
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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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