Fragile X Syndrome

Cortnee Hudson

What is Fragile X?

Also known as Martin-Bell Syndrome. FXS is a rare inherited genetic syndrome causing intellectual disability, and cannot be cured.

What Happens?

Fragile X Syndrome is caused by the expansion or lengthening of the FMR1 gene on the X chromosome(gene mutation).


Fragile X results in learning disabilities, developmental delays, and social or behavioral problems. Disabilities vary in severity. Physical features include large ears, a long face, a prominent jaw and forehead, flat feet, large ears, double jointed, lazy eye, and tremor. Behavior: aggression, hyperactivity, impulsiveness, nonsense word repetition, repetitive movements, and self harm.


"FXS is caused by a mutation in the FMR1 gene on the X chromosome. When the gene lengthens, it switches off production of a protein that is involved in brain development and other functions."

How can you get this Disorder?

"There is a place in the FMR1 gene where the DNA pattern CGG is repeated over and over again. In most people, the number of repeats is small (5 to 44 repeats), which is normal. If the number of repeats is too large (more than 20 repeats), the gene turns off. When the gene is turned off, no protein is made Without the protein, the person develops FXS. This is called a 'trinucleotide repeat disorder'. People get(inherit) the disorder from their parents."

How is it treated?

There is no cure for FXS as of now. Treatment may help. Therapy can be used to help with learning disabilities. Medications can be used for behavioral disorders.


"Mental Retardation is the hallmark of this condition and, in females, this may be the only sign of the problem. A specific genetic test (polymerase chain reaction [PCR]) can now be performed to diagnose fragile x syndrome. This test looks for an expanded mutation in the FMR1 gene."

Population Effects

"In many X linked conditions only males who inherit the abnormal gene are affected. FXS is one of the X linked conditions that can also affect females. In other cases, all males who carry the abnormal for of the gene are affected. In FXS, unaffected males can carry the gene in the premutation form while they have the conditions of the disorder."

"Fragile X syndrome is the most common inherited cause of intellectual disabilities, and most common known cause of autism. FXS affects 1 in 4000 males and 1 in 6000 females of all races and ethnic groups."

What I discovered...

That Fragile X syndrome is a disorder that leads to autism, and it is the most common inherited cause of intellectual disabilities. The symptoms are milder in females, than males.
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