19127 Health Library | Health and Wellness | Wellmont Health System
  • Risk Factors for Autism

    A risk factor is something that increases your likelihood of getting a disease or condition.
    You can develop autism with or without the risk factors listed below. However, the more risk factors you have, the greater your chance of developing autism. There is no known way to change your child's risk for autism.

    Genetic Factors

    Genetics is believed to play a role in the risk of autism. This is because the condition is more common in:
    • Families
    • Identical twins
    Recent studies have linked deletions in a section of chromosome 16. This chromosome abnormality may account for a small percentage of autism cases.


    Caucasian males are more likely to be affected by autism than females. But, when girls are affected, they may have more profound symptoms.

    Age of Parents

    Older parents (such as a woman over age 35) may have a higher risk of having a child with autism.

    Medical Conditions

    Autism occurs more frequently in children with rare genetic disorders or other medical conditions, including:
    • Tuberous sclerosis—A rare, multi-system genetic disease. It causes benign tumors to grow in the brain and on other vital organs. The organs include the kidneys, heart, eyes, and skin. It commonly affects the central nervous system. This results in a combination of symptoms. These include seizures, developmental delay, behavioral problems, skin abnormalities, and kidney disease.
    • Fragile X syndrome—A hereditary disorder of the X chromosome. It is the most common cause of inherited intellectual disability.
    • Neurofibromatosis—A genetic disorder of the nervous system. It causes tumors to grow on the nerves in any part of the body. Neurofibromatosis can also produce other abnormalities. These include changes in the skin and deformed bones.
    • Phenylketonuria (PKU)—A genetic disorder of the enzyme that breaks down phenylalanine. Phenylalanine is an amino acid found in certain foods. Without a proper diet, PKU can lead to intellectual disability.
    • Problems during pregnancy or delivery, including rubella—Rubella is a mild, highly contagious illness that is caused by a virus. The symptoms are a rash, swollen glands, and joint pain. If a pregnant woman has rubella, it can cause birth defects in her baby. Other possible risk factors include breech delivery and birth at less than 35 weeks gestation.
    • Epilepsy—This term refers to any disorder characterized by recurrent seizures. A seizure can have many symptoms. You may lose consciousness, stare into space, have convulsions (abnormal jerking of the muscles), or experience abnormalities of sensation or emotion.
    • Tourette’s syndrome
    • Newborn encephalopathy—This is a syndrome of disturbed brain function. It results in breathing difficulties, problems with reflexes, seizures, and other symptoms.
    • Moebius syndrome, cytomegalovirus, herpes encephalitis—These are sometimes listed as associated conditions.
    • Birth defects—Birth defects may also make a child more likely to develop autism.
    There has been a lot of press attention about a link between vaccines and autism. This is partly because of a vaccine preservative called thimerosol. But, studies have not found an association between vaccines and the development of autism.


    Autism Society of America. Autism 101 course. Autism Society of America website. Available at: http://www.autism-society.org/site/PageServer?pagename=about%5Fcourse. Accessed June 15, 2010.

    Autism spectrum disorders (pervasive developmental disorders). National Institute of Mental Health (NIMH) website. Available at: http://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-pervasive-developmental-disorders/index.shtml. Updated April 2008. Accessed September 11, 2008.

    Behrman RE, et al. Nelson Textbook of Pediatrics. 18th ed. Philadelphia: Saunders, 2007.

    DynaMed Editorial Team. Autistic disorder. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us. Updated September 13, 2010. Accessed September 14, 2010.

    Goetz CG. Goetz’s Textbook of Clinical Neurology. 3rd ed. Philadelphia, PA: Saunders; 2007.

    Jacobson JL, Jacobson AM. Psychiatric Secrets. 2nd ed. Philadelphia, PA: Hanley & Belfus, 2001.

    National Center on Birth Defects and Environmental Disabilities. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncbddd/index.html. Accessed June 23, 2008.

    Neonatal encephalopathy. Newborn Services Clinical Guideline website. Available at: http://www.adhb.govt.nz/newborn/guidelines/Neurology/NE.htm. Updated November 2004. Accessed June 16, 2010.

    Parker SK, Schwartz B, et al. Thimerosal-containing vaccines and autistic spectrum disorder: a critical review of published original data. Pediatrics. 2004;114(3):793-804.

    Rapin I. An 8-year-old boy with autism. JAMA. 2001;285:1749-1757.

    Stern TA, et al. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 1st ed. Philadelphia, PA: Mosby Elsevier; 2008.

    Wilson K, Mills E, et al. Association of autistic spectrum disorder and the measles, mumps, and rubella vaccine: a systematic review of current epidemiological evidence. Arch Pediatr Adolesc Med. 2003;157(7):628-634.

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