title: Cell-free fetal DNA in maternal plasma during physiological single male pregnancies: methodology issues and kinetics.
abstract: OBJECTIVE
  To analyze methodological influences and characterize the concentrations of cell-free fetal DNA (cffDNA) circulating in maternal plasma at different gestational ages in physiological pregnancies.
  
  
  METHODS
  We investigated 238 independent samples from single male-bearing pregnancies of different gestation age. In the other 50 pregnancies, the samples were collected three times during pregnancy (at all trimesters) to evaluate the kinetics of cffDNA. The manual and automated DNA extraction methods (Roche) were compared. cffDNA was amplified using real-time PCR method and Y-specific sequences SRY and DYS14. Total cell-free DNA circulating in maternal plasma was determined by the use of the GADPH sequence.
  
  
  RESULTS
  The elevation in the concentration of cffDNA during pregnancy with the highest value in the third trimester was observed independently on the DNA extraction method and on the Y-specific amplified sequence. The same is documented for the percentage of fetal DNA in total cell-free DNA in maternal plasma. It increases also in successive trimesters (8.3, 10.7 and 23.2%).
  
  
  CONCLUSIONS
  We discuss methodological problems and describe statistical parameters of cffDNA concentrations in maternal plasma during pregnancy as the basic information for comparison with pregnancies having a pathological outcome.
authors.affiliation: 3rd Medical Department, Charles University, Pilsen, Czech Republic.
authors.forename: Ales
authors.initials: A
authors.lastname: Horinek
authors.forename: Marie
authors.initials: M
authors.lastname: Korabecna
authors.forename: Ales
authors.initials: A
authors.lastname: Panczak
authors.forename: Zdenka
authors.initials: Z
authors.lastname: Ulcova Gallova
authors.forename: Kamila
authors.initials: K
authors.lastname: Nouzova
authors.forename: Pavel
authors.initials: P
authors.lastname: Calda
authors.forename: Miroslava
authors.initials: M
authors.lastname: Hancarova
mesh_terms: D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis / Q000379:methods; D004247:DNA / Q000097:blood*; D005260:Female; D005333:Fetus; D006801:Humans; D007700:Kinetics; D008297:Male; D008431:Maternal-Fetal Exchange; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First / Q000097:blood; D011262:Pregnancy Trimester, Second / Q000097:blood; D011263:Pregnancy Trimester, Third / Q000097:blood
chemical_list: D015415:Biomarkers; D004247:DNA