title: Further improvement in quantifying male fetal DNA in maternal plasma.
abstract: BACKGROUND
  Cell-free fetal DNA (cffDNA) in maternal plasma can be clinically useful for detecting prenatal disorders and pregnancy monitoring. More sensitive, specific, and quantitative detection of cffDNA in maternal plasma may expand the clinical utility of such measurements.
  
  
  METHODS
  We developed a quantitative real-time PCR (qPCR) assay [Y chromosome repetitive sequence (YRS) assay] based on a highly repetitive short sequence specific for the Y chromosome. Both standard qPCR and digital qPCR were performed to compare the sensitivity and specificity of this new assay against already established male DNA-specific assays.
  
  
  RESULTS
  The YRS assay was at least 10-fold more sensitive than the currently most sensitive DYS14 assay. The YRS assay was able to detect 0.5 genome equivalents (GE) per PCR reaction when fetal DNA was present at 0.2% of the total DNA. The background noise for the YRS assay was much lower than for the DYS14 assay in analyses of plasma samples from pregnancies with female fetuses.
  
  
  CONCLUSIONS
  The YRS assay is a substantial improvement for quantifying rare male fetal DNA in maternal plasma. The higher sensitivity and specificity may expand the clinical and research utility of cffDNA.
authors.affiliation: Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore.
authors.forename: Shengnan
authors.initials: S
authors.lastname: Jin
authors.forename: Xueqin Michelle
authors.initials: XM
authors.lastname: Lin
authors.forename: Haiyang
authors.initials: H
authors.lastname: Law
authors.forename: Kenneth Y C
authors.initials: KY
authors.lastname: Kwek
authors.forename: George S H
authors.initials: GS
authors.lastname: Yeo
authors.forename: Chunming
authors.initials: C
authors.lastname: Ding
mesh_terms: D041322:Chromosomes, Human, Y; D004247:DNA / Q000097:blood*; D005260:Female; D005333:Fetus; D006801:Humans; D008297:Male; D010949:Plasma; D011247:Pregnancy / Q000097:blood*; D011296:Prenatal Diagnosis / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D012680:Sensitivity and Specificity
chemical_list: D004247:DNA