What Is Fragile X Syndrome?
Reviewed: Dr. Gromatzky
4. Cause
Fragile X syndrome is the result of a mutation of the FMR1 gene, located on the X chromosome. This gene is normally responsible for making the fragile X mental retardation protein (FRMP). The body contains this protein in many locations, but it is especially abundant in the dendrites of neurons, where scientists believe it regulates the synthesis of other proteins.
A full mutation occurs in the FMR1 gene when a segment repeats over 200 times. This results in a non-functional gene that does not make a sufficient amount of FRMP and causes the symptoms of fragile X syndrome. A segment that repeats 50 to 200 times causes fragile X-associated tremor/ataxia syndrome or fragile X-associated primary ovarian insufficiency.
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