Fragile X Syndrome (FXS)

What is Fragile X Syndrome?

Fragile X Syndrome is a rare genetic disease characterized by mild to severe intellectual disability and psychiatric problems.

Both boys and girls can have the condition, with boys generally being more severely affected. Psychiatrically, there are autism spectrum problems, anxiety complaints and attention and concentration problems. Physically there are often enlarged testes, soft skin, hyperextension of the joints and repeated middle ear infections at a young age. There is also a slightly increased risk of heart defects and epilepsy. People with Fragile X Syndrome can have a large and long face with large protruding ears. In women, cognitive and psychiatric problems are usually milder, although 25% of women have an IQ below 70.

What Causes Fragile X Syndrome?

The Fragile X Syndrome is caused by an abnormality on the X chromosome. The FMR1 gene is located on the X chromosome. Mutations can gradually lengthen this gene, these are premutations. When the gene becomes too long, it is no longer read and no FMRP protein is produced. There is then a complete mutation.

Carriers of the premutation have an increased risk of having children with Fragile X Syndrome. Both the female and the male carriers of the premutation can develop a neurological syndrome with movement disorders at a later age, the Fragile X associated tremor / ataxia Syndrome: FXTAS. In addition, about a quarter of female carriers of the premutation may develop an early transition called Fragile X Associated Premature Ovarian Insufficiency: FXPOI.

How common is Fragile X Syndrome?

Fragile X Syndrome is a relatively common genetic cause of intellectual disability, and occurs in approximately 1: 3000 boys and 1: 7000 girls.

Examination and diagnosis

All patients who register will be discussed with the clinical geneticist. Sometimes it is necessary to do additional genetic research. This will of course be discussed in detail with you.

Explanation and counseling
When diagnosed with Fragile X Syndrome, people often need an explanation about the condition, the problems that may arise, how the condition originated, what this means for the child, but also for the environment and family. There is also often the question of what the risks are for any future children and other family members. If you have not yet had an extensive consultation with a clinical geneticist, or if you need more explanation, you are eligible for a counseling interview.

Family research
Fragile X syndrome is a genetic and genetic disease. Often this condition is inherited from generation to generation. Most carriers have no complaints. When a child is diagnosed with Fragile X Syndrome, it often means that family members have a chance to be carriers. Carrier can affect your health and that of your family. In addition, being a carrier means in some cases an increased risk of a child with Fragile X Syndrome. For that reason, family members are eligible for counseling and DNA testing.

The Fragile X consultation hour

Many parents have a need for an explanation about the syndrome after their child has been diagnosed with Fragile X Syndrome and there are often questions about their child's development or behavior. These questions keep recurring throughout the teenage years and into adulthood.

The expertise center, will help patients, families and caregivers by providing information, through targeted diagnostics and, where necessary, treatment or guidance. By seeing your child on a regular basis, we get to know your child and his / her environment better. This way we can help in a more targeted way if something goes wrong. In addition, we can also predict better how your child will develop further.

Emotional and / or behavioral problems
Many children and adults with Fragile X Syndrome suffer from anxiety complaints, behavioral problems and / or difficulty making contact. Often there is also an intellectual disability and learning difficulties. We have extensive experience in the diagnosis and treatment of anxiety and mood disorders, ADHD and autism, including in children with intellectual disabilities. We work with parents and patient to determine what help is needed. If possible, we provide this help ourselves, if necessary, we refer specifically to other care providers. For expertise in the field of adults with an intellectual disability, a Fragile X clinic has now been set up in Hoofddorp in collaboration with 's Heeren Loo.

Physical problems
Children and adults with Fragile X Syndrome are generally physically healthy. Slightly weaker bands around the joints can sometimes cause complaints. Starting heart valve abnormalities can sometimes be found in teenagers. However, it is sometimes not easy to determine whether complaints are related to the Fragile X Syndrome or are separate from it. Your child will be seen and examined by the expert team's pediatrician. Here you have the opportunity to ask questions about any physical complaints and to discuss with the pediatrician whether further investigation is necessary and how and where this can best be done. We strive to better map physical complaints and problems with Fragile X Syndrome.

The Fragile X Expertise Center is a multidisciplinary collaboration in which the departments of Child and Adolescent Psychiatry / Psychology, Clinical Genetics, Pediatrics, Neurology, Medicine for the Mentally Handicapped and Neurosciences work closely together in the field of patient care and in the scientific field. The Fragile X Expertise Center is embedded in the ENCORE Expertise Center of Erasmus MC

Caregivers for children

Child and Adolescent Psychiatrist and Coordinator: Dr. Bram Dierckx
GZ psychologist: Dr. André Rietman
Pediatrician: Dr. Carsten Lincke
Klinisch geneticus: Dr. S. Zeidler, Dr. Anneke Kievit

Caregivers for adults:

GDPR: Dr. Agnies van Eeghen
Psychiatrist, GZ psychologist: Dr. Michiel Coesmans
Internist Genetic Congenital Disorders: Dr. Laura de Graaff
Klinisch geneticus: Dr. Zeidler, Dr. Anneke Kievit


Click here  to go to the contact form or mail yourself to:
By telephone: outpatient clinic of child and adolescent psychiatry of the Erasmus MC at number 010 -704.02.09 and ask for Dr. Dierckx


Click here  to go to the contact form or mail yourself to:
Applications / referrals can be sent to attn Dr. L. de Graaff and Dr. A.M. van Eeghen

In order to provide the best possible care to patients with a rare condition, it is essential that global knowledge about the condition is gathered. Nationwide, centers of expertise have been set up to stimulate care for rare disorders and to gather knowledge. For the formal recognition of an expertise center by the Ministry of Health, an important condition is that the expertise center gathers, analyzes and shares knowledge through publications. These can be publications in scientific journals, but also treatment guidelines for health care professionals or information brochures for patients or caregivers. We optimize care and research within ENCORE through standardized follow-up and close collaboration between doctors and researchers. That way, we can ultimately develop better treatments for rare conditions. You may therefore be asked to participate in research. Participation in research is always on a voluntary basis. The data obtained is stored and analyzed in an anonymous form. All research has been approved in advance by an ethics review committee.

To learn more about research into Fragile X Syndrome at ENCORE, clicking here

There is a patient organization for people with Fragile X Syndrome, Fragile X Association Netherlands, clicking here to go to the website.

More information about the diagnosis and treatment within our expertise centercan be found in our 'Guideline for diagnosis and treatment of children with Fragile X Syndrome' (only in Dutch). .