CJG Blog

Center for Jewish Genetics blog

Similarities and Differences in Fragile X Syndrome and Autism

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Most people have heard of autism, but many are not familiar with an associated disorder: Fragile X syndrome (FXS). Fragile X syndrome is the leading genetic cause of autism and the most common cause of inherited intellectual disability. According to the Centers for Disease Control and Prevention, Fragile X and other genetic or chromosomal conditions are responsible for about 10 percent of autism cases.1 On the other hand, nearly half of all males with FXS have also been diagnosed with autism.2

While there is overlap between the two conditions, there are also key differences. In honor of July as Fragile X Awareness Month, we’re shedding some light on the causes, symptoms and treatment of Fragile X syndrome and its link to autism spectrum disorders.

Cause: Fragile X is caused by a genetic mutation in the FMR1 gene on the X chromosome. The causes of autism are less clear.

Like other X-linked conditions, Fragile X syndrome is caused by a genetic mutation on the X chromosome and typically is passed down from carrier mothers to male children. Females have two X chromosomes, which means that females with a mutated FMR1 gene usually also have a working copy of the gene. Because this working copy compensates for the changed copy, females may be carriers of Fragile X but typically are not affected by it. When females are affected, they are more likely to exhibit milder symptoms than males with Fragile X. Males only have one X chromosome and therefore a male with a mutation in the FMR1 gene will have the disorder.

Unlike with FXS, there’s no one cause of autism spectrum disorders. Research shows that a combination of genetic changes and environmental factors may increase a person’s risk of autism.3 While the genetics of autism are not yet well understood, there’s evidence to suggest that autism may run in families.3

Symptoms: Individuals with Fragile X often have intellectual disabilities. Individuals with autism have difficulties with social interactions and communication.

Although symptoms of Fragile X and autism spectrum disorders overlap, FXS is characterized by intellectual disability and developmental delays while autism is defined by challenges with social interaction and language impairment. Since some individuals have both disorders, the line between signs of FXS and autism can be blurry. Even those who don’t have both disorders may exhibit similar symptoms, such as repetitive behaviors and poor eye contact.

Symptoms of both Fragile X and autism range in severity. Some individuals may experience relatively mild symptoms while others have more severe forms of the disorder(s).

Treatment: There currently is no cure for Fragile X syndrome or autism spectrum disorders. However, early intervention and treatment can help.

While there currently is no cure for Fragile X or autism, early intervention may help improve a child’s development.4 If your family is affected by one or both of these disorders, a team of doctors and health professionals can work with you to develop an individualized treatment plan that best meets your needs.  

In some cases, genetic testing may provide a diagnosis that can help guide treatment. Fragile X testing is recommended for those with a family history of the disorder and for individuals with autism. Fragile X testing is often performed in conjunction with a microarray (another genetic test) for children with autism, intellectual disability, or developmental delay of unknown cause.  Carrier screening for Fragile X is also available to all women preconception and included as part of the Center’s screening program unless otherwise requested.

Questions? Our genetic counselor is your resource in the community for information about Fragile X and genetic testing.


  1. https://www.cdc.gov/ncbddd/autism/data.html
  2. https://www.cdc.gov/ncbddd/fxs/data.html
  3. https://www.autismspeaks.org/what-autism/learn-more-autism/what-causes-autism
  4. https://www.cdc.gov/ncbddd/fxs/facts.html

Photo credit: Darryl Leja, NHGRI


Meet Community Health Educator Becca Bakal, MPH

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From Becca: 

I am honored to be joining the Norton & Elaine Sarnoff Center for Jewish Genetics as a Community Health Educator. I grew up in Barrington, Illinois and then moved to New Haven, Connecticut for college. I majored in Women’s, Gender, & Sexuality Studies before going on to complete a Master’s in Public Health in a joint BA/MPH program at Yale University. I have a background in health education, particularly sexual and reproductive health as well as obesity prevention. I’m thrilled to be able to apply my health education background in the Chicagoland Jewish community, which has always been a home to me. My current pastimes include going to farmers markets and getting lost while exploring the city.

Please reach out to me at RebeccaBakal@juf.org or 312-357-4717. 

Making Sense of Medical Literature

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By Jason Rothstein, MPH









Be a Gen(e)ius About Your Genetic Health

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3D Genome

By Amy Weinstein

There are many ways to be proactive about your health, including your genetic health. Healthy eating habits and regular exercise may improve your general health and wellbeing. When it comes to genetic health, carrier screening and learning your family health history can help you assess your risk and provide information to help you make informed decisions. Keeping track of your health is important for everyone, including members of the Jewish community, who have increased risk for certain genetic disorders and hereditary cancers.

One way to be proactive about your health is to eat responsibly. Experts recommend eating a fiber filled breakfast, and adding fresh fruits and vegetables to your meals. Regular exercise also provides health benefits. Personal trainers state that it’s important to make exercising a habit especially for beginners1. Try to set new goals for yourself and create more challenging workouts.

If you’re planning for a family, carrier screening is another important way to be proactive about your health. According to the CDC, 80% of babies with genetic diseases are born to parents with no known history of that disease2. That’s because people can carry genetic mutations and not know it. Carriers usually do not develop the disorder, but are at risk of passing the disorder down to a child. If both parents carry the same genetic mutation, with each pregnancy, their child will have a 50% chance of being a carrier, a 25% chance of being affected, and 25% chance of neither being affected nor being a carrier. Whether the results are positive or negative, genetic screening and genetic counseling can provide couples with information they need to make informed decisions. Carrier couples have many options for creating a healthy family. Even patients who choose not to alter their family approach may benefit from knowledge that can help them prepare if a future child needs early intervention.

While carrier screening can help you be proactive about the health of your future family, learning your family health history provides insight into your own risk of disease. Collecting medical information about your parents, grandparents and siblings is one way to identify patterns and potential risk factors. You can share that information with your medical provider, who will provide guidance on any next steps to reduce risk.

The Norton & Elaine Sarnoff Center for Jewish Genetics offers resources to help you start that conversation. Our genetic counselor is also available to answer questions, provide information and help direct you to appropriate resources.  


1. http://www.fitnessmagazine.com/workout/tips/the-new-get-fit-rules-exercise-dos-and-donts/

2. https://www.ncbi.nlm.nih.gov/books/NBK11795/

Image from https://www.flickr.com/photos/genomegov/


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