The true impact of fragile X syndrome

How often are women carriers of fragile X syndrome? Results from an exceptionally large, ethnically diverse population.

There has been limited data published on population-wide carrier testing for FXS, and this has meant conservative criteria for identifying women who should be offered testing.

We studied a large, ethnically diverse patient population of >130,000 women to help fill in this gap.

What did we find?

  • About 1 in 200 women are carriers of a FXS premuation.1
  • This means providers are 2 to 4X more likely to deliver a baby with FXS than with SMA.
  • This also means providers are equally as likely to deliver a baby with FXS as with CF.
This research was published in the American Journal of Medical Genetics (Mar. 2018). Read the manuscript
A summary of these results and what they mean for your practice. Download the infographic


  1. Owens KM, et al. FMR1 premutation frequency in a large, ethnically diverse population referred for carrier testing. Am J Med Genet A. 2018 Jun;176(6):1304-1308.