Fragile X Syndrome (FAQ)

Answers to questions families often have about caring for their child with fragile X syndrome

What is fragile X syndrome and what causes it?

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disabilities and a common known cause of autism. It may not be immediately apparent that a person has fragile X syndrome as symptoms, such as learning problems, autism, and anxiety, and some physical features, can be subtle.

What are the symptoms of fragile X syndrome?

Males are usually more affected than females. Features may include: intellectual disabilities, ranging from mild learning disabilities to intellectual disability, attention deficit and hyperactivity, anxiety and unstable mood, autistic behaviors and/or sensory integration problems, such as hypersensitivity to loud noices or bright lights, speech delay, with expressive language more severely affected than receptive language, and seizures. Physical features are usually hard to recognize in babies and young children, but sometimes become more apparent with age: long face, large ears, flat feet, hyperextensible joints, low muscle tone, and in adult men, large testes.

How is it diagnosed?

Testing for fragile X is done by a simple and reliable DNA blood test. This test is widely available, so talk with your doctor.

What is the prognosis?

Prognosis will depend on your child's symptoms now. Children who are mildly affected at diagnosis may be less affected as adults than children with severe symptoms at diagnosis.

What is the risk for other family members or future babies?

Fragile X syndrome occurs when there is an expansion of the genetic material in a specific place on the X chromosome. The chances of having a second child with fragile X increase if the mother has a larger expansion, and can be as high as 50% if the second child is male. This should be discussed with your doctor as the risks can be better estimated with more information about the mother's genetic material. Prenatal testing for fragile X is available.

What treatments/therapies/medications are recommended or available?

There is currently no cure for fragile X, although appropriate education and medications can help maximize the potential of each child. However, most boys and many girls remain significantly affected throughout their lives.

I have been told that my child has fragile X syndrome (FXS), but he has no signs of autism. Could the doctors be wrong?

Only about 20% of children with fragile X syndrome exhibit significant autistic behaviors, so it is very possible for a child to have fragile X syndrome and not have autism. Autistic behaviors include poor eye contact, hand-flapping, self-injurious behavior, and poor sensory skills.

Why am I being tested for fragile X syndrome; it is my son who has the disorder?

Extended family members of individuals with fragile X syndrome may have related disorders, including social problems, learning disabilities, premature ovarian failure, and fragile X-associated trem/ataxia syndrome, depending on gene status. Screening is sometimes done on extended family members to provide proactive care for problems that may arise as well as to give genetic counselors more information so that they may better counsel a family regarding recurrence risk.


Information & Support

Related Portal Content
Fragile X Syndrome
Assessment and management information for the primary care clinician caring for the child with fragile X syndrome (FXS).
Care Notebook
Medical information in one place with fillable templates to help both families and providers. Choose only the pages needed to keep track of the current health care summary, care team, care plan, health coverage, expenses, scheduling, and legal documents. Available in English and Spanish.

For Parents and Patients

Fragile X Syndrome (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

FRAXA Research Foundation
Along with funding research, FRAXA runs scientific meetings, advises pharmaceutical companies, and provides education. Families can reach out to FRAXA for resources, guidance, referrals, and an international community of support.

National Fragile X Foundation
A non-profit organization run by parents of children with fragile X syndrome that supports research and families caring for children with fragile X syndrome.

Services for Patients & Families in New Mexico (NM)

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.


Fenobam (FRAXA Research Foundation)
Although in the early stages, fenobam, a selective mGluR5 antagonist, may be helpful in individuals with fragile X syndrome. So far, it has been tested only in adults.

Fragile X (
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

Authors & Reviewers

Initial publication: March 2012; last update/revision: September 2015
Current Authors and Reviewers:
Author: Lynne M. Kerr, MD, PhD
Funding: The Medical Home Portal thanks the 2011-2012 URLEND Medical Home Portal trainees group for their contribution to this page.