What is the prevalence of Fragile X Syndrome (FXS)?

Fragile X Syndrome has been detected in all populations and ethnic groups. As a result, efforts have been made to determine the overall prevalence of FXS and the difference in prevalence between males and females.

There have been a number of studies aimed at determining the prevalence of FXS in males and females. Studies have been undertaken both in the “special needs” population and the general population. The agreed upon prevalence of FXS:

  • Males — approximately 1 in 3,600 to 4,000.
  • Females — approximately 1 in 4,000 to 6,000.

While researchers do not have an exact number for how many Americans (males and females) could have the full-mutation Fragile X syndrome, the ratios noted above suggest that the raw number of individuals could be as low as 38,000 or as high as 87,000. (Worldwide, the number could be between 777,000 and 1,400,000.) However, it’s important to note that some published papers suggest greater prevalence and some lower prevalence than the numbers cited above.

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