title: DNA sequencing versus standard prenatal aneuploidy screening.
abstract: BACKGROUND
  In high-risk pregnant women, noninvasive prenatal testing with the use of massively parallel sequencing of maternal plasma cell-free DNA (cfDNA testing) accurately detects fetal autosomal aneuploidy. Its performance in low-risk women is unclear.
  
  
  METHODS
  At 21 centers in the United States, we collected blood samples from women with singleton pregnancies who were undergoing standard aneuploidy screening (serum biochemical assays with or without nuchal translucency measurement). We performed massively parallel sequencing in a blinded fashion to determine the chromosome dosage for each sample. The primary end point was a comparison of the false positive rates of detection of fetal trisomies 21 and 18 with the use of standard screening and cfDNA testing. Birth outcomes or karyotypes were the reference standard.
  
  
  RESULTS
  The primary series included 1914 women (mean age, 29.6 years) with an eligible sample, a singleton fetus without aneuploidy, results from cfDNA testing, and a risk classification based on standard screening. For trisomies 21 and 18, the false positive rates with cfDNA testing were significantly lower than those with standard screening (0.3% vs. 3.6% for trisomy 21, P<0.001; and 0.2% vs. 0.6% for trisomy 18, P=0.03). The use of cfDNA testing detected all cases of aneuploidy (5 for trisomy 21, 2 for trisomy 18, and 1 for trisomy 13; negative predictive value, 100% [95% confidence interval, 99.8 to 100]). The positive predictive values for cfDNA testing versus standard screening were 45.5% versus 4.2% for trisomy 21 and 40.0% versus 8.3% for trisomy 18.
  
  
  CONCLUSIONS
  In a general obstetrical population, prenatal testing with the use of cfDNA had significantly lower false positive rates and higher positive predictive values for detection of trisomies 21 and 18 than standard screening. (Funded by Illumina; ClinicalTrials.gov number, NCT01663350.).
authors.affiliation: From the Mother Infant Research Institute, Tufts Medical Center and Tufts University School of Medicine, Boston (D.W.B.); Lyndhurst Clinical Research, Winston-Salem, NC (R.L.P.); the Group for Women, Norfolk, VA (J.W.); Long Island Jewish Medical Center, North Shore-LIJ Health Systems, New Hyde Park, NY (R.M.); West Coast OB/GYN, San Diego (C.S.), InClin, San Mateo (A.F.D.), and Illumina, Redwood City (D.I.C., P.L.D., K.W.J., K.O., R.P.R., A.J.S.) - all in California; and Colorado Permanente Medical Group, Denver (J.A.C.).
authors.forename: Diana W
authors.initials: DW
authors.lastname: Bianchi
authors.forename: R Lamar
authors.initials: RL
authors.lastname: Parker
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Wentworth
authors.forename: Rajeevi
authors.initials: R
authors.lastname: Madankumar
authors.forename: Craig
authors.initials: C
authors.lastname: Saffer
authors.forename: Anita F
authors.initials: AF
authors.lastname: Das
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Craig
authors.forename: Darya I
authors.initials: DI
authors.lastname: Chudova
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Devers
authors.forename: Keith W
authors.initials: KW
authors.lastname: Jones
authors.forename: Kelly
authors.initials: K
authors.lastname: Oliver
authors.forename: Richard P
authors.initials: RP
authors.lastname: Rava
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Sehnert
mesh_terms: D000328:Adult; D000782:Aneuploidy; D025063:Chromosome Disorders / Q000175:diagnosis / Q000235:genetics; D002882:Chromosomes, Human, Pair 13 / Q000235:genetics; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics; D005189:False Positive Reactions; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D062145:Maternal Serum Screening Tests; D048208:Nuchal Translucency Measurement; D010949:Plasma; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012307:Risk Factors; D017422:Sequence Analysis, DNA / Q000379:methods; D014314:Trisomy / Q000175:diagnosis* / Q000235:genetics; D000073839:Trisomy 13 Syndrome; D000073842:Trisomy 18 Syndrome