Fragile x Syndrome

A Rare Condition

What Is Fragile X Syndrome?

Fragile x syndrome is sex linked genetic disorder is carried on the x chromosome. Fragile X Syndrome causes mild to severe intellectual disabilities. It affects both males and females, but females usually have milder symptoms.

Why Haven't I Heard Of It ?

FXS is actually a rare genetic condition with fewer than 200,000 U.S cases per year.

1 in 4,000 males & 1 in 8,000 females will have Fragile X Syndrome.

1 in 468 males & 1 in 151 females has the premutation.

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Males have XY chromosomes while females have XX chromosomes. Fragile X Syndrome is carried on the x chromosome, not the y. So, If a male has the defective trait on the x chromosome, there is no other gene that works correctly.That is why when males have fragile x it is more likely to be severe than females. When females have one defective gene on the x chromosome they can have another x chromosome that functions correctly, so the symptoms would be milder. If a female has the defective genes on both chromosomes then the symptoms are more likely to be moderate to severe.

Wait! You Never Mentioned The Symptoms!

Oops, well here are the symptoms:

-Delayed Speech

-Long and Narrow Face

-Anxiety

-Large Ears

-Hyperactive Behavior

-A Prominent Jaw/Forehead

-Seizures

-Flexible Fingers

-Flat Feet

-Enlarged Testicles a/or Breast Development (males)


*(also common: lazy eye, scoliosis, Tremors, Single line on the palm, sunken chest)


NOTE:As the child gets older the physical characteristics of Fragile X Syndrome become more prominent, which is shown in the example below.

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How Exactly Is It Caused??

Fragile x is caused by a missing protein, FMRP that is vital for brain function.


NOTE: Genes are named after they are discovered.

FMR1 actually stands for "Fragile X Syndrome Mental Retardation Gene" since it was the known cause of Fragile X Syndrome.

What is the FMR1 Gene & How Does It Relate to FXS?

The FMRI gene is usually found in the brain and in the nerves. It is used to maintain connection between cells in the brain and the nervous system. Fragile X Syndrome is caused by the absence or reduced amount of the FMR1 protein, FMRP. The most common cause of FXS is by the repetition pattern "CCG" in the DNA. This repetition leads to DNA methylation and silencing of the FMR1 gene. As a result, FMRP is not produced and that causes Fragile X syndrome.


  • The picture shows the area where the FMRP protein is not present due to the silencing of the FMR1 gene


NOTE: The deletion of the FMR1 can also cause Fragile X Syndrome

How Many "CCG" repeats is needed to have FXS?

The number off "CCG" repeats dictates if a person has the premutation or the full FMR1 mutation.


Less than 45 "CCG" repeats = normal gene


45-54 "CCG" repeats = Gray zone. Individuals in the grey zone aren't known to pass on the mutation nor to develop it into the future.


52-200 "CCG" repeats=premutation. This means that later in life an individual can develop Fragile x Syndrome or it can be passed down. Most likely, as the premutated gene is passed down from generation to generation it will eventually develop into the full mutation. For example, if a mother has the permutation it is possible that when she has a child, the child will have Fragile x Syndrome.


More than 200 "CCG" repeats= full mutation

How Is it Inherited?

FXS is a sex-linked disorder that is carried on the x chromosome. The trait can be passed from parent to child depending on who has the mutation.

It can be shown using a pedigree or a diagram that shows the inheritance of a certain trait through several generations

How Is Fragile X Syndrome Diagnosed?

Fragile X syndrome can be diagnosed while the child is still inside the womb by prenatal testing. Prenatal testing involves risk to the fetus as well as the mother, so it should be discussed with your health care provider. Here are the prenatal test that can be conducted:

  • Amniocentesis -a sample of the amniotic fluid or fluid that surrounds the fetus within the amnion and it is tested for the FMR1 mutation.
  • Chorionic Villus-A health care provider takes a sample of cells from the placenta or circular organ in the uterus that nourishes the fetus through the umbilical cord and the cells are tested for the mutation.


Parents may also notice the delayed development in their child or toddler. If a health care provider believes that their infant /child has fragile x the health care provider would refer the child to a clinical geneticist that can perform an genetic test for FXS.


NOTE: RISKS AND BENEFITS OF PRENATAL TESTNG SHOULD BE DISCUSSED WITH YOUR DOCTOR.

Is there A Cure for Fragile x Syndrome??

No, there isn't a cure for Fragile X Syndrome, but there are different treatments that may help with the symptoms


Educational Treatments:

Most children with FXS can benefit from special education services that are tailored to their particular strengths and weaknesses. FXS children are eligible for free public education according to federal law, but having a medical diagnosis does not guarantee access to special education services.


Therapy Treatments

Several different specialist can help manage the symptoms of fragile x syndrome.

  • Speech-Language Therapist

  • Occupational Therapist
  • Physical Therapist
  • Behavioral Therapist


Medications

There are different medicines that are prescribed to deal with different symptoms of fragile X Syndrome, since there isn't one specific medication or cure for it.


medication name (brand)


  • Folic acid

  • Baclofen

  • Risperidone (Risperdal)

  • Clonidine (Nexiclon)

  • Aripiprazole (Abilify),

  • Memantine (Namenda),

  • Guanfacine (Intuniv)

NOTE:THIS CHART IS MEANT FOR REFERENCE ONLY AND SHOULD NOT TAKE THE PLACE OF A HEALTH CARE PROVIDER'S ADVICE. ANY QUESTIONS SHOULD BE DISCUSSED WITH YOUR HEALTH CARE PROVIDER.

Whats The Best Option For Treatment?

A combination of special education, medications and therapies is the most effective way to help deal with fragile x syndrome. It is the best way to hone skills and expand abilities. Treatment are designed to help the child learn effectively, so the earlier the treatment is given is the better.

Can You Sum That All Up?

Fragile x syndrome is a sex liked genetic disorder that causes mild to severe intellectual disabilities and females tend to have milder symptoms. Fragile X is caused by the repetition of " CCG" repeats in the DNA. Too many repeats causes the silencing of the FMR1 and the protein it produces FMRP. FRM1 is used to maintain connection between the brain and nerve cells, if they are not produced it causes Fragile x Syndrome. Furthermore,The number of "CCG" repeats in the DNA dictates if the person has the full mutation or if they are carriers of FXS. More than 200 repeats means the person has the full mutation & 52-200 is a premutation.


The symptoms of FXS are delayed speech and hyperactive behavior. Physical characteristics include long and narrow face and prominent forehead or jaw. The diagnosis of FXS can be through prenatal testing or if a clinical geneticist runs a genetic test. Treatments include special education, therapies and medicines. The combination of these treatments is the best option for maximum results.

Where Did You Get Your Information From?

Written By: Princess

Date: March 18,2016