August 24, 2022


October 13, 2022

Prenatal Screening for Fragile X Syndrome

Prenatal testing can help determine if your baby will have certain conditions or birth defects like Fragile X Syndrome. Learn the details here.

Medically reviewed by

Dr. Nicolette Natale

Doctor of Osteopathic Medicine

When you're pregnant, it's normal to have a lot of thoughts about what your baby will be like—what their personality will be like, what color their eyes might be, et cetera. But the more important question is whether your baby will be healthy. We're lucky to live in a time when we can find out about potential complications beforehand.

You can find out whether your baby will have Fragile X syndrome long before your due date so that you can plan accordingly for the future. After learning about Fragile X syndrome, you'll be better equipped to decide if prenatal testing is right for you. 

A brief overview

Fragile X syndrome, also known as Martin-Bell syndrome, is a genetic disorder that causes a range of physical deformities, developmental delays, behavioral impairments, and intellectual disabilities. Physical features may include large ears, a long face, a prominent jaw and forehead, or flat feet. It's caused by a mutation of the FMR1 gene on the X Chromosome. In a person who doesn't have Fragile X syndrome, 40 short, repeating sequences of CGG nucleotides exist within the gene. There are 200 or more CGG repetitions in a person with the condition.

Prevalence is higher in males (approximately 1 in 3,600 to 4,000) than in females (about one in 4,000 to 6,000), and its presentation is usually more severe. Carriers of the mutation may experience Fragile X-associated primary ovarian insufficiency (FXPOI), which encompasses infertility, early menopause, irregular menstrual periods, or reduced fertility.

They may also experience Fragile X-associated tremor/ataxia syndrome (FXTAS), which includes symptoms such as balance issues, shakiness, poor memory, moodiness, cognitive dysfunction, and numbness in the hands and feet.

What does the test involve?

Two types of prenatal tests are used to determine whether a fetus has Fragile X: chorionic villus sampling (CVS) and amniocentesis. Both ‌tests have some risks you must consider before deciding what to do.

CVS is a genetic test that involves taking a sample of cells from the placenta. They're formed from the fertilized egg and have the same genetic material as the developing baby. When the sample is taken through the vagina, a speculum is used to open the vaginal wall and view the cervix. At the same time, a doctor inserts a small tube into the cervix and collects the sample. Another method involves using an ultrasound to visualize your placenta and then your doctor will insert a needle through the abdomen for collection. Your health care provider may give you a local anesthetic to lessen the discomfort of this procedure.

An amniocentesis tests for Fragile X using amniotic fluid. To get the sample, your health care provider inserts a needle through the abdomen into the uterus and withdraws a small amount of amniotic fluid for testing.

CVS and amniocentesis come with some rare but potentially serious risks, including:

  • Temporary amniotic fluid leaking
  • Needle injury to the fetus
  • Uterine infection
  • Rh sensitization
  • Infection transmission to the fetus
  • Miscarriage

How to find out if you're a carrier

Carriers may not have the features associated with Fragile X syndrome. Still, they have the potential to pass the condition to their children. To find out if you're a carrier, you can take a simple genetic test, which uses either blood, saliva, or a cheek swab. The test determines how many CGG repeats you have. Talk to your doctor about getting a Fragile X carrier screen.

Under 45 repeats: Negative. Not considered a carrier of Fragile X because of an expanded CGG region.

Between 45 and 55 repeats: Intermediate. Not at risk of passing it on or developing associated health issues, but the condition may present in the next few generations.

Between 55 and 200 repeats: Premutation. At the risk of passing on the condition and may develop FXPOI and/or FXTAS.

200 or more repeats: Full Fragile X mutation resulting in the gene shutting off and becoming silent. Men usually exhibit symptoms, while only half of the women with a full mutation show signs of an intellectual disability. Not at risk of developing FXPOI or FXTAS.

What are the risk factors?

The more CGG repeats a person has, the more likely their children will have Fragile X syndrome and the more severe their symptoms are. When a person has an unusual number of CGG repeats, that number increases for each future generation.

Prenatal testing isn't common practice for pregnant women. Certain risk factors increase your chances of passing Fragile X to your child. Your doctor may recommend prenatal testing if you're over 35 or have a family history of:

  • Fragile X
  • Adult-onset tremors/ataxia
  • Intellectual disabilities
  • Developmental delay
  • Autism of unknown cause
  • Infertility problems because of premature ovarian failure (POF) or elevated follicle stimulating hormone (FSH)

Treatment options for Fragile X syndrome

There is no cure for Fragile X syndrome, but you can minimize the symptoms with various methods. Therapy aims to help patients using behavioral strategies, and medication may help with regular sleep, emotions, and attention. A combination of therapy and medication often improves symptoms.

Therapeutic strategies include:

  • Occupational therapy
  • Speech therapy
  • Physical therapy

Effective medications include:

  • Mood stabilizers
  • Stimulants
  • Selective Serotonin Reuptake Inhibitors (SSRIs)
  • Anxiolytics
Stem cell transplants show exciting developments in improving outcomes for those with Fragile X. With human embryonic stem cells, researchers have found a way to reactivate a silenced FMR1 gene using a particular activator protein. Once the protein attaches to the repeat, the gene can function again.

Bank your stem cells with Anja Health

Anja Health can safely store the potentially life-saving stem cells found in your umbilical cord blood and tissue. Cord blood and tissue have the potential to effectively treat a variety of genetic conditions that were previously thought to be untreatable. Getting a Stem Cell Safe is simple, and you can trust that the future of your child's health is in excellent hands.

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