title: Three peaks in the polymerase chain reaction fragile X analysis.
abstract: OBJECTIVE
  To report and discuss the observation of three fragments on polymerase chain reaction (PCR) in routine carrier screening for fragile X.
  
  
  METHODS
  From 2005 through 2010, 34,500 women underwent prenatal screening for fragile X. PCR was carried out to amplify the repeat segment. The resulting fragments were scanned by a genetic analyser.
  
  
  RESULTS
  Three PCR peaks representing three different-sized fragments were found in 25 of the 34,500 women (1:1380 or 0.072%). Karyotype analysis was performed in 16 subjects. Full triple X was found in three women, while two had triple X mosaicism. Of the 16 karyotyped women, five (31%) had a finding of XXX (full or mosaic).
  
  
  CONCLUSIONS
  Triple X (full or mosaic) is the most frequently encountered mechanism responsible for three peaks on fragile X PCR testing.
authors.affiliation: The Genetic Institute and Ob/Gyn Department, Meir Medical Center, Kfar Saba, Israel. Sharony@clalit.org.il
authors.forename: Reuven
authors.initials: R
authors.lastname: Sharony
authors.forename: Atalia
authors.initials: A
authors.lastname: Shtorch
authors.forename: Aliza
authors.initials: A
authors.lastname: Amiel
authors.forename: Esther
authors.initials: E
authors.lastname: Guetta
authors.forename: Leah
authors.initials: L
authors.lastname: Peleg
authors.forename: Elon
authors.initials: E
authors.lastname: Pras
authors.forename: Liat
authors.initials: L
authors.lastname: Ries-Levavi
mesh_terms: D000483:Alleles; D041321:Chromosomes, Human, X / Q000235:genetics*; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007621:Karyotyping; D009030:Mosaicism; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods