Fragile X syndrome

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at September 1, 2016
StartDiseasesFragile X syndrome

Fragile X syndrome is an extremely rare genetic disorder with a range of symptoms that affect a person's cognition. Males have this X-linked dominant disorder more often than females.


Definition & Facts

Fragile X syndrome is a condition that occurs genetically that causes a range of problems within the development of a person which can include disabilities in learning and impairment of cognitive functions. Cognitive functions are the activities within a person's brain that allow them to gain and retain information. This includes a person's memory, reasoning, language, and attention. A third of males with Fragile X syndrome have symptoms associated with autism spectrum disorders.

Symptoms & Complaints

Not everyone with Fragile X syndrome has the same symptoms. The symptoms that are seen in females are most commonly milder than the symptoms that are seen in males. A great number of people that have Fragile X syndrome have issues with learning and development. The different learning issues can include:

The majority of infants and young children with Fragile X syndrome do not have any physical symptoms, but as they grow older and begin to go through puberty, there are some physical symptoms that many will experience, including:

Most children with Fragile X syndrome have some sort of challenge associated with emotional and social functioning which can include the following symptoms:

  • Not easily being able to make eye contact with others
  • A new situation can make them anxious or afraid
  • They may be aggressive or have problems paying attention
  • Being shy around people they do not know

Most boys that have Fragile X syndrome have some type of issue with their language or speech, such as having a stutter when they talk.

Many children are also sensitive to different sensations, such as loud noises (noise sensitivity), bright lights (light sensitivity), and even the way certain types of clothing feels on their skin. These issues can cause children with Fragile X syndrome to act out and display issues with their behavior.


Fragile X syndrome is caused by a genetic mutation of the FMR1 gene that is found within the X chromosome, which is a sex chromosome. Every person has sex chromosomes, and there are two different types, the X chromosome and the Y chromosome. Males have an X chromosome and a Y chromosome, while females have two X chromosomes.

The mutation that occurs within the gene does not allow for the X chromosome to make the protein, FMRP which is in the brain and sex organs and plays a vital role in the function of the central nervous system. Without the proper amount of protein, Fragile X syndrome occurs.

Diagnosis & Tests

If there are developmental delays within a child, whether it is sitting, crawling, walking, or talking, Fragile X syndrome may be the cause. Now all children develop at their own pace, but when the delays become significant, testing may need to be done to determine if this syndrome is the reason for it.

Another thing that may trigger the need for testing is if there are any physical signs of the syndrome, such as a larger head circumference than normal or differences in a child's facial features. Many children do not show physical signs of the syndrome until they hit puberty, but there are some that do. Once the physical signs are noticed, testing should be done.

If any of these symptoms are noticed, the child should be brought to their physician. If the physician believes that Fragile X syndrome may be the cause of the child's symptoms, they will have the child tested. A sample of blood will be taken and tested to determine whether or not the patient has the FMR1 gene. If the gene is found, it will verify that the patient has Fragile X syndrome. This test can detect the gene in both males and females.

Treatment & Therapy

Fragile X syndrome is not a condition that can be cured, but there are treatment options that can help with the symptoms of the syndrome. Treatment will vary depending on the severity of the symptoms as well as what the symptoms are.

For those that have learning disabilities, there are therapy options that will help as well as special education services that are available. Behavior therapy is also available for those patients that have difficulties with social situations. The therapy is used to help the patient break any unhealthy habits they have and will teach them the proper way to act in social situations. Cognitive behavior therapy is one form of psychotherapy that may be of assistance in helping a child develop tools. Speech therapy may also help address any speech disorders or language disorders the child is coping with.

Medications are also available and can be prescribed depending on the symptoms of the patient. For those that have anxiety, depression, hyperactivity, or attention disorders, medication can help to ease symptoms. Such psychiatric medications could include antidepressants like selective serotonin reuptake inhibitors to treat depression, amphetamine to treat attention deficit hyperactivity disorder, anxiolytics like lorazepam and diazepam to treat anxiety.

Occupational therapy and physical therapy may also be recommended to assist the child in developing skills that will improve his or her quality of lfe.

Prevention & Prophylaxis

Fragile X syndrome is a condition that is caused by a genetic mutation, so it cannot be prevented. If the syndrome is something that runs in the family, a person can have genetic testing done in order to determine if they are a genetic carrier of the syndrome.

Being a carrier does not mean that the person has the syndrome themselves, but if they were to have children, they could pass the genetic mutation onto their children. Some people that are carriers will choose not to have children in order to eliminate the risk of passing it on.

Some carriers may also decide to use genetic counseling in order to help them determine the risks of passing the syndrome onto their children.