title: RHD allelic identification among D-Brazilian blood donors as a routine test using pools of DNA.
abstract: BACKGROUND
  RHD alleles leading to a reduced expression of D antigen of the red blood cell (RBC) surface may be erroneously typed as D- by serology and may cause anti-D immunizations when transfused to recipients.
  
  
  METHODS
  To determine the occurrence of such alleles among apparent D- blood donors, molecular typing was implemented as a routine test using a pool of DNA. A total of 2,450 pretyped D- samples were tested in pools of 10 for the RHD-specific polymorphism in intron 4 and exon 7. Samples in polymer chain reaction (PCR) positive pools were individually reevaluated by exon-specific PCRs, sequencing, and serologic methods.
  
  
  RESULTS
  Among 2,450 serologically D- blood donor samples tested, 101 (4.1%) carried the RHD gene. Nonfunctional RHD (RHDψ, RHD*CE(2-9)-D, and RHD*CE(3-7)-D), different weak D alleles such as RHD*weak D type 1, RHD*weak D type 4.3, RHD*weak D type 5, RHD*weak D type 38, and RHD*DEL were identified.
  
  
  CONCLUSIONS
  We employed a PCR-based assay for RHD as a routine test using pools of ten DNA blood donor samples. The integration of RHD genotyping into the routine screening program using pools of DNA samples was straightforward. As a consequence, 19 (0.8%) blood donors carrying a weak D and Del phenotypes with the potential of causing anti-D immunizations in recipients were reclassified as D+. For each population, it would be necessary to adapt the RHD genotyping strategy to the spectrum of prevalent alleles.
authors.affiliation: Department of Hemotherapy, Albert Einstein Hospital, São Paulo, SP, Brazil. marizamota@einstein.br
authors.forename: Mariza
authors.initials: M
authors.lastname: Mota
authors.forename: M
authors.initials: M
authors.lastname: Dezan
authors.forename: M C
authors.initials: MC
authors.lastname: Valgueiro
authors.forename: A M
authors.initials: AM
authors.lastname: Sakashita
authors.forename: J M
authors.initials: JM
authors.lastname: Kutner
authors.forename: L
authors.initials: L
authors.lastname: Castilho
mesh_terms: D000483:Alleles; D001782:Blood Donors; D001938:Brazil; D004247:DNA / Q000235:genetics*; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D058889:Molecular Typing / Q000379:methods*; D011110:Polymorphism, Genetic; D012204:Rh-Hr Blood-Group System / Q000235:genetics*
chemical_list: D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen; D004247:DNA