Preconceptional and prenatal screening for fragile X syndrome: Experience with 40 000 tests

Michal Berkenstadt*, Liat Ries-Levavi, Howard Cuckle, Leah Peleg, Gad Barkai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

Objectives: To determine the carrier frequency of fragile X syndrome, and the rate of expansion from premutation (PM) carrier to full mutation (FM) fetus. Methods: Results were analyzed on women with no family history of fragile X syndrome, or who were PM/FM carriers, who were tested between January 1994 and June 2004. PM was defined 55-199 repeats, FM above 200. Results: Out of 40079 women screened, 5 FM and 255 PM carriers were detected. There was no significant difference in carrier frequency between those with versus those without family history of mental retardation or developmental abnormalities: 1 in 128 (28/3596) versus 1 in 157 (232/36483). However, the median of repeats differed significantly: 58 and 66 repeats, respectively, (P < 0.0001). Invasive prenatal diagnosis was carried out in 370 pregnancies (7 FM and 363 PM). Thirty FM fetuses were detected. There was a lower expansion rate in cases without a family history: 10% (17/169 PMs) compared to 50% (11/22 PMs) in those with a history, but this could be accounted for by the difference in allele size. Conclusion: There is now sufficient information on screening parameters and prenatal diagnosis of fragile X syndrome to offer testing to women of reproductive age.

Original languageEnglish
Pages (from-to)991-994
Number of pages4
JournalPrenatal Diagnosis
Volume27
Issue number11
DOIs
StatePublished - Nov 2007
Externally publishedYes

Keywords

  • CGG repeat number in the FMR1 gene
  • FM of fragile X syndrome
  • Fragile X syndrome
  • Premutation of fragile X
  • Prenatal diagnosis of fragile X syndrome
  • Screening for fragile X syndrome

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