title: Direct detection of fetal cells in maternal blood: a reappraisal using a combination of two different Y chromosome-specific FISH probes and a single X chromosome-specific probe.
abstract: BACKGROUND
  We have recently explored the detection of circulatory male fetal cells directly in maternal whole blood samples by fluorescence in-situ hybridization (FISH). In order to improve the efficacy of fetal cell detection, we have now examined whether this could be enhanced by the use of two different Y chromosome-specific FISH probes (alpha-satellite and classical satellite III regions) in combination with an X chromosome-specific FISH probe.
  
  
  METHODS
  Nineteen maternal blood samples (median gestational age = 28 weeks, range = 12-37 weeks) were examined in a blinded manner. No enrichment procedure was performed. Following hypotonic treatment and Carnoy's fixation, total nucleated cells were examined by two color FISH with a single X and two Y chromosome-specific probes. Nine cases were examined in parallel by conventional XY-FISH.
  
  
  RESULTS
  Fetal cell detection was superior when using two Y chromosome-specific probes (specificity = 75%; sensitivity = 91%) when compared to the conventional XY-FISH approach (specificity = 50%; sensitivity = 60%).
  
  
  CONCLUSIONS
  Male fetal cells can be detected in most maternal blood samples examined. Specificity and sensitivity is improved when using a combination of single X and two Y chromosome-specific probes when compared to a conventional XY-FISH protocol.
authors.affiliation: Laboratory for Prenatal Medicine, University Women's Hospital/Department of Research, Spitalstr. 21, 4031, Basel, Switzerland.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Babochkina
authors.forename: Susanne
authors.initials: S
authors.lastname: Mergenthaler
authors.forename: Tatyana Maier
authors.initials: TM
authors.lastname: Dinges
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Holzgreve
authors.forename: Sinuhe
authors.initials: S
authors.lastname: Hahn
mesh_terms: D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D005260:Female; D005333:Fetus / Q000166:cytology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000097:blood; D011262:Pregnancy Trimester, Second / Q000097:blood; D011263:Pregnancy Trimester, Third / Q000097:blood; D011296:Prenatal Diagnosis; D012680:Sensitivity and Specificity