FMR1 premutation frequency in a large, ethnically diverse population referred for carrier testing

Kailey M. Owens, Lindsay Dohany, Carol Holland, Jeana DaRe, Tobias Mann, Christina Settler, Ryan E. Longman

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and is caused by an expansion of cytosine-guanine-guanine (CGG) repeats in the FMR1 gene. Female premutation allele carriers (55–200 CGG repeats) are at risk to have an affected child. Currently, specific population-based carrier screening for FXS is not recommended. Previous studies exploring female premutation carrier frequency have been limited by size or ethnicity. This retrospective study provides a pan-ethnic estimate of the Fragile X premutation carrier frequency in a large, ethnically diverse population of women referred for routine carrier screening during a specified time period at Progenity, Inc. Patient ethnicity was self-reported and categorized as: African American, Ashkenazi Jewish, Asian, Caucasian, Hispanic, Native American, Other/Mixed/Unknown, or Sephardic Jewish. FXS test results were stratified by ethnicity and repeat allele category. Total premutation carrier frequency was calculated and compared against each ethnic group. A total of 134,933 samples were included. The pan-ethnic premutation carrier frequency was 1 in 201. Only the Asian group differed significantly from this frequency. Using the carrier frequency of 1 in 201, a conservative pan-ethnic risk estimate for a male fetus to have FXS can be calculated as 1 in 2,412. This risk is similar to the highest ethnic-based fetal risks for cystic fibrosis and spinal muscular atrophy, for which population-wide screening is currently recommended. This study adds to the literature and supports further evaluation into specific population-wide screening recommendations for FXS.

Original languageEnglish (US)
Pages (from-to)1304-1308
Number of pages5
JournalAmerican Journal of Medical Genetics, Part A
Issue number6
StatePublished - Jun 2018


  • carrier frequency
  • carrier screening
  • fragile X syndrome
  • premutation allele

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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