← All diseases

Genetic syndromes and other conditions

Fragile X syndrome

An inherited disease caused by a gene change on the X chromosome. It causes learning difficulties and behavior problems. Boys are usually more severely affected.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

Orphanet has a guideline for emergency doctors for this disease (language: French, Spanish). See on Orphanet

Prepare an emergency card

This page is translated from the Turkish original.

This disease is followed through the “Genetic syndromes and other conditions” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

In a gene called FMR1, a small piece of DNA is repeated too many times. When this happens, the gene is switched off and the FMRP protein cannot be made. This protein is needed for the connections between nerve cells. As a result, brain development and learning are affected.

Which symptoms can occur?

Symptoms are usually more marked in boys.

  • Delayed speech up to the age of 2
  • Mild or moderate learning difficulties (in most boys and about a third of girls)
  • Anxiety, hyperactivity and attention problems
  • Autism-like features (in about a third)
  • Seizures (sometimes)
  • A long face, large ears, flexible joints and flat feet

How is it diagnosed?

In infancy, there are very few visible signs. The disease is suspected when there is delayed development or differences in behavior. The diagnosis is made with a blood test that looks at the FMR1 gene.

Treatment and care

There is no approved treatment specific to the disease; research on medicines is ongoing. Special education and skills training help the child develop as well as possible. Symptoms are also dealt with as they appear. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through the X chromosome. In some people, the gene is not fully faulty; this is called a pre-change, or premutation. In the children of a mother who carries a premutation, the gene can become even longer. Because of this, these mothers have a higher risk of having an affected child. Men who carry a premutation pass this gene only to their daughters. If there is a family history, genetic counselling is recommended.

Source: MedlinePlus Genetics: Fragile X syndrome · MedlinePlus: Fragile X syndrome

Key facts

How common is it?
Prevalence: 1-5 per 10 000 (Worldwide)
How is it inherited?
X-linked dominant
When does it usually start?
Childhood, Infancy, Newborn period
Gene(s) involved
FMR1

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

We could not find a patient association specific to this disease.

For all rare diseases: Nadir Hastalıklar Federasyonu

Guides related to this disease

  • Rare disease at school · Telling the school, medicines and emergency plan, inclusion and BEP, support education room, absences, LGS/YKS arrangements, peer bullying.

Support and help

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about Fragile X

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

  • Could this trial be suitable for us?
  • If we take part, how would current treatment and check-ups be affected?
  • Where does the trial take place, and how are travel and accommodation handled?
  • What happens if we want to leave the trial?

ClinicalTrials.gov lists 20 active interventional studies for this disease. 12 are recruiting now; none has a site in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

See all studies on ClinicalTrials.gov · Joining clinical trials

Genetic syndromes and other conditions: other news

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:908 · ICD-11 LD55

Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.

The information on these pages is for general information only and does not replace medical advice. Talk to your doctor about diagnosis and treatment decisions. In an emergency in Türkiye, call 112.

Every update is based on an open source and labeled with its level of evidence. No advertising and no drug brand names. Our scientific principles

This page was translated from Turkish by the Doktorclub editorial team.