What are the other Names for this Condition? (Also known as/Synonyms)

• FXS (Fragile X Syndrome)
• Marker X Syndrome
• Martin-Bell Syndrome 

What is Fragile X Syndrome? (Definition/Background Information)

• Fragile X Syndrome (FXS) is a genetic condition characterized by intellectual development challenges due to changes in parts of the X (sex) chromosome. The syndrome is caused by mutations to the FMR1 gene on the X chromosome
• This gene codes the instructions for making the FMR protein necessary for normal  brain growth. When mutations are present, the body does not produce the protein or makes too little of it, resulting in intellectual disabilities
• While most cases of Fragile X Syndrome are inherited, the syndrome may occur as a sporadic disorder (if there is no family history of the disorder). Genetic testing is the best method to diagnose this disorder
• The common signs and symptoms of Fragile X Syndrome are mental retardation, speech/language delays, difficulty learning, and hyperactive behavior. It is often associated with other developmental disorders, including autism
• There is no cure or prevention of Fragile X Syndrome. The outcome of individuals with the disorder highly depends on the severity of mental retardation

Who gets Fragile X Syndrome? (Age and Sex Distribution)

• Fragile X Syndrome is an X-linked genetic disorder, which means that male children are more likely to inherit the disorder than female children, because they only have one X chromosome (females have two X chromosomes)
• In females, both the X chromosome should have FMR1 gene mutations for the symptoms to appear
• Fragile X Syndrome manifests at birth; however, it may take a few years for the symptoms to become apparent

What are the Risk Factors for Fragile X Syndrome? (Predisposing Factors)

The risk factors associated with Fragile X Syndrome include:

• Male gender: Males are more prone because Fragile X Syndrome is an X-linked genetic disorder. Since males have only one X chromosome, the FMR1 gene mutations present on the X chromosome, will result in symptoms. Females are less likely to develop symptoms because they have two X chromosomes (if one is mutated, the other X chromosome still functions normally)
• Since Fragile X Syndrome is a genetic disorder, a family history of the disorder increases the likelihood of a child developing the disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider. 

What are the Causes of Fragile X Syndrome? (Etiology)

• Fragile X Syndrome is caused by mutations in the FMR1 gene on X chromosome. Normally, this gene codes for the production of the fragile X retardation protein (FMRP), which is essential for normal brain growth
• When mutation is present, the FMR1 protein is either not produced, or is produced at levels that are too low for normal brain development. If the FMRP protein is not present, brain development cannot occur normally. Due to this, mental retardation and other intellectual problems are common in individuals with FXS
• In females, mutation in one X chromosome does not produce any symptoms, because the second normal X chromosome will produce normal levels of FMR1 protein needed for brain development

What are the Signs and Symptoms of Fragile X Syndrome?

The signs of symptoms may vary from one individual to another. Some individuals have mild symptoms, while others may have severe symptoms. The common signs and symptoms of Fragile X Syndrome include:

• Mental retardation
• Speech/language delays
• Difficulty learning
• Delays in crawling, walking
• Hyperactive behavior (ADD)
• Flatfeet
• Low muscle tone
• Large forehead, long face
• Protruding ears and chin
• Loose joints

The signs and symptoms may develop few years after birth in certain babies. 

How is Fragile X Syndrome Diagnosed?

The diagnosis of Fragile X Syndrome may include:

• A complete evaluation of medical and family history and a thorough physical examination
• The most common method to diagnose FXS is through DNA testing using a blood test. PCR (a type of test) can be conducted, looking for expanded mutations in the FMR1 gene
• It is often difficult to diagnose Fragile X syndrome in infants. Usually, infants with the disorder have an abnormally large head circumference and develop slower than usually. This may be the first indication about the presence of this disorder

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis. 

What are the possible Complications of Fragile X Syndrome?

Complications in individuals with Fragile X Syndrome greatly vary and they depend on the severity of the signs and symptoms. The complications may include:

• The individuals may experience recurrent infections as children
• Seizure disorder may also develop in individuals with Fragile X Syndrome
• The syndrome is also often associated with other developmental disorders, including autism

How is Fragile X Syndrome Treated?

Currently, there is no cure for Fragile X Syndrome. The treatment is aimed at managing the symptoms and to help individuals maintain the highest possible functioning level. These treatment measures may include:

• Speech therapy
• Physical therapy
• Social therapy
• Medications, to control other symptoms

How can Fragile X Syndrome be Prevented?

• Currently, there are no specific methods or guidelines to prevent Fragile X Syndrome, since it is a genetic condition
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Fragile X Syndrome? (Outcomes/Resolutions)

• The outcome of individuals with Fragile X Syndrome depends very much on the severity of mental retardation
• With proper intervention, treatment, and education, individuals can learn to function to near normal levels within the society 

Additional and Relevant Useful Information for Fragile X Syndrome:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/congenital-genetic-disorders/