title: Noninvasive prenatal testing for fetal trisomies in a routinely screened first-trimester population.
abstract: OBJECTIVE
  We sought to assess performance of noninvasive prenatal testing for fetal trisomy in a routinely screened first-trimester pregnancy population.
  
  
  METHODS
  This was a cohort study of 2049 pregnant women undergoing routine screening for aneuploidies at 11-13 weeks' gestation. Plasma cell-free DNA analysis using chromosome-selective sequencing was used. Laboratory testing on a single plasma sample of 2 mL was carried out blindly and results were provided as risk score (%) for trisomies 21 and 18.
  
  
  RESULTS
  Trisomy risk scores were given for 95.1% (1949 of 2049) of cases including all 8 with trisomy 21 and 2 of the 3 with trisomy 18. The trisomy risk score was >99% in the 8 cases of trisomy 21 and 2 of trisomy 18 and <1% in 99.9% (1937 of 1939) of euploid cases.
  
  
  CONCLUSIONS
  Noninvasive prenatal testing using chromosome-selective sequencing in a routinely screened population identified trisomies 21 and 18 with a false-positive rate of 0.1%.
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, King's College, London, England, UK.
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
authors.forename: Argyro
authors.initials: A
authors.lastname: Syngelaki
authors.forename: Ghalia
authors.initials: G
authors.lastname: Ashoor
authors.forename: Cahit
authors.initials: C
authors.lastname: Birdir
authors.forename: Gisele
authors.initials: G
authors.lastname: Touzet
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D002887:Chromosomes, Human, Pair 18; D015331:Cohort Studies; D004247:DNA / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D062145:Maternal Serum Screening Tests / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood*; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA / Q000379:methods*; D014314:Trisomy / Q000175:diagnosis*
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D004247:DNA; D011266:Pregnancy-Associated Plasma Protein-A