title: Accurate and robust quantification of circulating fetal and total DNA in maternal plasma from 5 to 41 weeks of gestation.
abstract: BACKGROUND
  Detection of fetal DNA in maternal plasma is achievable at 5 weeks of gestation, but few large-scale studies have reported circulating fetal and maternal DNA across all trimesters.
  
  
  METHODS
  Blood samples were collected from 201 women between 5 and 41 weeks of pregnancy. Quantitative PCR was used to assess total and fetal DNA concentrations, and allelic discrimination analysis was investigated as a route to detecting specifically fetal DNA.
  
  
  RESULTS
  Male fetuses were detectable from 5 weeks amenorrhea with increasing fetal DNA concentrations across gestation. The sensitivity of fetal male gender determination in pregnancies with live birth confirmation was 99%, with 100% specificity. Total DNA concentrations did not correlate with gestational age, but appeared slightly higher in the first and third trimesters than in mid-pregnancy. Analysis of short tandem repeats demonstrated that significant improvements in the detection limit are required for specific detection of fetal DNA.
  
  
  CONCLUSIONS
  The high sensitivity of PCR-based detection, together with quantification provided by real-time DNA analysis, has clear potential for clinical application in noninvasive prenatal diagnosis. However, accurate quantification using best-fit data analysis, standardization of methods, and performance control indicators are necessary for robust routine noninvasive diagnostics.
authors.affiliation: BioAnalytical Innovation Team, LGC Ltd., Teddington, United Kingdom.
authors.forename: Lyndsey
authors.initials: L
authors.lastname: Birch
authors.forename: Claire A
authors.initials: CA
authors.lastname: English
authors.forename: Keelin
authors.initials: K
authors.lastname: O'Donoghue
authors.forename: Olivia
authors.initials: O
authors.lastname: Barigye
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Fisk
authors.forename: Jacquie T
authors.initials: JT
authors.lastname: Keer
mesh_terms: D000367:Age Factors; D004247:DNA / Q000097:blood* / Q000235:genetics; D005260:Female; D005333:Fetus; D005865:Gestational Age; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy / Q000097:blood*; D011264:Pregnancy Trimesters; D011296:Prenatal Diagnosis / Q000379:methods; D020080:Tandem Repeat Sequences; D013997:Time Factors
chemical_list: D004247:DNA