title: Clinical application of midtrimester non-invasive fetal RHD genotyping and identification of RHD variants in a mixed-ethnic population.
abstract: OBJECTIVE
  This study aims to assess the suitability of non-invasive prenatal RHD genotyping in non-immunized midtrimester pregnant women from a mixed ethnic population, to prevent unnecessary anti-D immunoglobulin prophylaxis and to identify RHD variants
  
  
  METHODS
  Rhesus D-negative pregnant women were offered fetal RHD genotyping at 24 gestational weeks. A total of 284 samples were tested for RHD status using multiplex rt-PCR amplification of exons 5 and 7 of the RHD gene and exons 6 and 10 in selected cases. Women carrying RHD-negative fetuses were counseled about their option to avoid routine antenatal anti-D immunoglobulin administration. Diagnostic accuracy of RHD genotyping was compared with postnatal Rhesus D serotyping.
  
  
  RESULTS
  A total of 184 positives (65%), 91 negatives (32%) and 7 cases (2.5%) compatibles with RHD variants were detected by RHD genotyping. No false negative results were found, and a single false positive was observed in a twin pregnancy. Genotyping was accepted when offered by 94% of women (284/302), and anti-D immunoglobulin was avoided in 95% (90/95) of RHD-negative fetuses.
  
  
  CONCLUSIONS
  Non-invasive routine antenatal RHD genotyping at 24 weeks of pregnancy is a highly accurate method, resulting in the avoidance of 95% of unnecessary administrations of anti-D immunoglobulin, with no false negative results.
authors.affiliation: Department of Maternal-Fetal Medicine, Institute Gynecology, Obstetrics and Neonatology, Hospital Clínic Barcelona, Catalonia, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Grande
authors.forename: E
authors.initials: E
authors.lastname: Ordoñez
authors.forename: V
authors.initials: V
authors.lastname: Cirigliano
authors.forename: J
authors.initials: J
authors.lastname: Cid
authors.forename: E
authors.initials: E
authors.lastname: Grau
authors.forename: A
authors.initials: A
authors.lastname: Pericot
authors.forename: I
authors.initials: I
authors.lastname: Teixido
authors.forename: J L
authors.initials: JL
authors.lastname: Marin
authors.forename: A
authors.initials: A
authors.lastname: Borrell
mesh_terms: D005091:Exons; D005260:Female; D005312:Fetal Blood; D060005:Genotyping Techniques; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D044469:Racial Groups / Q000235:genetics; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D013030:Spain
chemical_list: D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen