How Is Fragile X Syndrome Diagnosed

How Is Fragile X Syndrome Diagnosed?

How Is Fragile X Syndrome Diagnosed?

Fragile X syndrome (FXS) is a genetic disorder that affects cognitive, social, and physical development. Fragile X syndrome affects cognitive function, which can result in learning deficits in individuals and cause difficulties at home or in school for children. Early intervention and tailored management work well in providing individuals with FXS with coping mechanisms and behavioral skills to handle the complications and difficulties of this syndrome, and diagnosing FXS early is essential for these early interventions. The Special Olympics Arizona team is breaking down the methods and procedures used to diagnose Fragile X syndrome, from prenatal testing to childhood diagnoses.

Prenatal Testing

Pregnant women who have an FMR1 permutation or a full mutation may pass that mutated gene on to their children, and a prenatal test allows healthcare providers to detect this mutated gene if it is present in a developing fetus. Prenatal testing for Fragile X syndrome is available for these individuals with a family history of the disorder or for mothers who are known carriers. Prenatal testing is not very common, since it does involve some minor risks to the mother and the fetus. If you or a family member are considering prenatal testing, it is important to discuss all the risks and benefits with your healthcare provider. The two types of prenatal tests that may be used in a diagnosis include:


Amniocentesis is a procedure that typically takes place in the second trimester of pregnancy, around 15 to 20 weeks. It involves the collection of a small sample of amniotic fluid, which surrounds the developing fetus. The fluid is analyzed to determine if the FMR1 gene, which is linked to FXS, is expanded.

Chorionic Villus Sampling (CVS)

Chorionic villus sampling is performed earlier in pregnancy, typically between 10 and 13 weeks. It involves obtaining a small piece of placental tissue, which also contains genetic information. Like amniocentesis, CVS can help identify the expansion of the FMR1 gene.

Diagnosing Fragile X Syndrome in Children

Since prenatal testing is not very common and many parents are unaware that they carry the mutation, it is much more common for Fragile X syndrome to be diagnosed in childhood, as it becomes more apparent when developmental milestones are not met. Several factors are considered when making the diagnosis, including parents noticing symptoms of delayed development in their infants or toddlers. These symptoms could include delays in speech and language skills, social and emotional difficulties, and sensitivity to certain sensations or other sensory difficulties. Children may be delayed in their development of motor skills, such as learning to walk. If you notice some of these symptoms or difficulties in your baby or child, speaking with your pediatrician and getting a referral to a specialist could be the first step towards a diagnosis and early intervention if your child is diagnosed with FXS. It is worth noting that many of the symptoms associated with FXS could be symptoms of other cognitive disorders, such as autism, ADHD, or other common diagnoses. It is important to speak to a professional before making any at-home diagnosis for your child.

At What Age Are Kids Usually Diagnosed With Fragile X Syndrome?

Children with Fragile X syndrome are often diagnosed between the ages of 3 and 5. At this stage, developmental delays and other symptoms of fragile X syndrome may become more noticeable. However, some individuals may not receive a diagnosis until later in childhood or adolescence.

Who Diagnoses Fragile X Syndrome?

Fragile X syndrome can be diagnosed by healthcare professionals, including pediatricians, geneticists, neurologists, and developmental specialists. The diagnosis may involve the following steps:

  • Clinical Assessment: A comprehensive clinical assessment considers an individual’s medical and family history, developmental milestones, and behavioral traits.
  • Genetic Testing: A simple blood test can identify the expansion of the FMR1 gene, which is associated with Fragile X syndrome. This test can determine whether an individual has the full mutation or a premutation.
  • DNA Analysis: DNA analysis is used to evaluate the number of CGG repeats in the FMR1 gene. A full mutation typically has more than 200 CGG repeats.

Questions to Help Diagnose Fragile X Syndrome

When diagnosing Fragile X syndrome in children, healthcare professionals may consider various questions and criteria, such as:

  • Does the child have developmental delays or intellectual disabilities?
  • Are there difficulties with language and speech development?
  • Are there behavioral challenges, such as anxiety, hyperactivity, or social difficulties?
  • Does the family have a history of Fragile X syndrome or intellectual disabilities?

The diagnostic process is often collaborative, involving input from multiple healthcare professionals and specialists. Early diagnosis is critical for accessing appropriate support, therapies, and interventions to help individuals with Fragile X syndrome reach their full potential. While there is no cure for fragile X syndrome, there are a number of therapies, special education options, and other intervention options that can be incorporated into your care plan to ensure your child is able to live a happy and healthy life.

Diagnosing Fragile X syndrome can take place during pregnancy if there is a known family history, but many individuals are unaware they are carriers and as such, their child will be diagnosed through genetic testing and clinical assessment during early childhood or beyond. Early diagnosis enables individuals with FXS and their families to access the necessary resources and support to manage the condition effectively. The Special Olympics Arizona team offers a wealth of information and resources for individuals with FXS and their families. To learn more about interventions and therapy options, community building options, and gaining support from the Special Olympics Arizona team, visit our website or contact a member of the team.

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