A risk factor is something that increases your likelihood of getting a disease or condition.
You can develop
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.
Genetics is believed to play a role in the risk of autism. This is because the condition is more common in:
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.
Older parents, such as a woman over age 35, may have a higher risk of having a child with autism.
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
- Fragile X syndrome
—A hereditary disorder of the X chromosome. It is the most common cause of inherited intellectual disability.
—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.
(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
Problems during pregnancy or delivery, including
—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.
—This term refers to any disorder characterized by recurrent seizures. A seizure can have many symptoms. You may lose consciousness, stare into space, have 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.
cytomegalovirus, herpes encephalitis—These are sometimes listed as associated conditions.
- Birth defects—Birth defects may also make a child more likely to develop autism.
- Fetal alcohol syndrome—Caused when a mother drinks alcohol during pregnancy. It can cause birth and developmental defects in the child.
- Angelman syndrome—A genetic disorder that affects the nervous syndrome and causes delayed development, intellectual disability, speech problems, and problems with movement and balance.
- Rett syndrome—A problem with the development of the nervous syndrome. It is most common in girls.
- Smith-Lemli-Opitz—A metabolic disorder caused by a gene mutation. People with the disorder cannot make enough cholesterol.
- West syndrome—Causes a specific type of seizure seen in an epilepsy syndrome of infancy
There has been much attention around 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 101: a free online course. The Autism Society website. Available at:
http://support.autism-society.org/site/PageServer?pagename=about_course. Accessed May 14, 2013.
Autism spectrum disorders. EBSCO DynaMed website. Available at:
https://dynamed.ebscohost.com/about/about-us. Updated May 6, 2013. Accessed May 14, 2013.
Autism spectrum disorders (ASDs). Centers for Disease Control and Prevention website. Available at:
http://www.cdc.gov/ncbddd/autism/index.html. Updated August 7, 2012. Accessed May 14, 2013.
Autism spectrum disorders (pervasive developmental disorders). National Institute of Mental Health website. Available at:
http://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-pervasive-developmental-disorders/index.shtml. Updated May 14, 2013. Accessed May 14, 2013.
Behrman RE, et al.
Nelson Textbook of Pediatrics. 18th ed. Philadelphia: Saunders, 2007.
Goetz’s Textbook of Clinical Neurology. 3rd ed. Philadelphia, PA: Saunders; 2007.
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Psychiatric Secrets. 2nd ed. Philadelphia, PA: Hanley & Belfus, 2001.
Neonatal encephalopathy. Newborn Services Clinical Guideline website. Available at:
http://www.adhb.govt.nz/newborn/guidelines/Neurology/NE.htm. Accessed May 15, 2013.
Parker SK, Schwartz B, et al. Thimerosal-containing vaccines and autistic spectrum disorder: a critical review of published original data.
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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.
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Last reviewed May 2013 by Kari Kassir, MD;
Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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