The exact number of people with a premutation is unknown. Research shows that about 1 in 259 females and 1 in 813 males may have an FMR1 gene premutation, which puts them at risk for FXTAS.1 But not everyone with a premutation will show symptoms.
FXTAS is less common among women, and their symptoms are generally milder.2
In people with a premutation, 30% to 40% of men older than 503 and 8% of women older than age 50 will develop FXTAS.4
- Hersh, J. H., Saul, R. A., & Committee on Genetics. (2011). Health supervision for children with fragile X syndrome. Pediatrics 127, 994–1006. [top]
- National Fragile X Foundation (n.d.). FXTAS vs FXS. Retrieved May 7, 2012, http://www.fxtas.org/fxtas_vs_fxs.htm [top]
- Jaquemont, S., Hagerman, R. J., Leehey, M. A., Hall, D. A., Levine, R.A., Brunberg, J. A., et al. (2004) Penetrance of the fragile X associated tremor/ataxia syndrome in a premutation carrier population. Journal of the American Medical Association, 291,460–469. [top]
- National Fragile X Foundation. (2011). Prevalence of FXTAS. Retrieved May 7, 2012, from http://www.fxtas.org/prevalence.htm [top]