title: Accuracy of fetal gender determination in maternal plasma at 5 and 6 weeks of pregnancy.
abstract: OBJECTIVE
  To assess the viability of the early diagnosis of fetal gender in maternal plasma before 7 weeks of pregnancy by real-time polymerase chain reaction (real-time PCR), starting at 5 weeks of pregnancy.
  
  
  METHODS
  Peripheral blood was collected from pregnant women, starting at 5 weeks of gestation. After centrifugation, plasma was separated for fetal DNA extraction. DNA was analyzed by quantitative real-time PCR for two genomic regions, one on the Y chromosome (DYS-14) and the other shared by both sexes (ss-globin), by the TaqMan Minor Groove Binder (MGB) probe assay. The results of the examinations were compared to fetal gender determined after delivery.
  
  
  RESULTS
  A total of 79 examinations of fetal DNA in maternal plasma were performed for 52 pregnant women. Accuracy according to gestational age was 92.6% (25 of 27 cases) at 5 weeks, and 95.6% (22 of 23 cases) at 6 weeks. These results also demonstrate that fetal DNA is present at low concentrations in maternal plasma at 5 weeks (8.5 genome equivalents (GE)/mL) and 6 weeks (34.1 GE/mL) of pregnancy.
  
  
  CONCLUSIONS
  Quantitative real-time PCR and TaqMan MGB probes specific for the detection of fetal gender in maternal plasma starting at 5 weeks of gestation have good sensitivity and excellent specificity.
authors.affiliation: CPDP - Paulista Center of Diagnosis and Research - Ribeirão Preto, SP Brazil.
authors.forename: Ciro Dresch
authors.initials: CD
authors.lastname: Martinhago
authors.forename: Ricardo Manoel
authors.initials: RM
authors.lastname: de Oliveira
authors.forename: Maria do Carmo
authors.initials: Mdo C
authors.lastname: Tomitão Canas
authors.forename: Laura Diniz
authors.initials: LD
authors.lastname: Vagnini
authors.forename: João Batista
authors.initials: JB
authors.lastname: Alcantara Oliveira
authors.forename: Claudia Guilhermino
authors.initials: CG
authors.lastname: Petersen
authors.forename: José Gonçalves
authors.initials: JG
authors.lastname: Franco Junior
mesh_terms: D041322:Chromosomes, Human, Y; D004247:DNA / Q000097:blood* / Q000235:genetics; D005260:Female; D005333:Fetus / Q000196:embryology*; D005865:Gestational Age; D006801:Humans; D008297:Male; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood* / Q000235:genetics; D011268:Pregnancy-Specific beta 1-Glycoproteins / Q000235:genetics; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D012732:Sex Determination Analysis / Q000379:methods*
chemical_list: D011268:Pregnancy-Specific beta 1-Glycoproteins; D004247:DNA