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What is Fragile X syndrome?

The term Fragile X refers to a group of conditions due to defects in a gene on
the X chromosome:

  • Fragile X syndrome (FXS)
  • Fragile X-associated Tremor Ataxia Syndrome (FXTAS)
  • Fragile X-associated primary ovarian insufficiency (FXPOI)

Fragile X syndrome (FXS), first known as Martin-Bell syndrome, is the most common inherited form of mental impairment. FXS affects 1 in 4,000 boys and 1 in 6,000 girls of all races and ethnic groups. While Fragile X individuals have a normal life expectancy, most will need support and care for their entire lives.

A single gene in the brain cells shuts down, causing Fragile X syndrome. In 1991, scientists discovered the defect in a gene on the X chromosome (called FMR1)
that causes FXS. In affected individuals, this gene is shut down and cannot manufacture the protein it normally makes – a protein vital for normal brain development and functioning.

Large-scale population studies of Fragile X still need to be done, but it is clear that this is one of the most common genetic diseases in humans. Most people with Fragile X are not yet correctly diagnosed.

Research is aimed at developing effective treatments. In addition, this research is leading to better understanding and treatments for other conditions, such as autism, and Alzheimer’s Disease.

Consider testing any individual with:

  • unexplained developmental delay
  • mental impairment
  • autism