title: Changing practice: red blood cell typing by molecular methods for patients with sickle cell disease.
abstract: BACKGROUND
  Extended red blood cell (RBC) antigen matching is recommended to limit alloimmunization in patients with sickle cell disease (SCD). DNA-based testing to predict blood group phenotypes has enhanced availability of antigen-negative donor units and improved typing of transfused patients, but replacement of routine serologic typing for non-ABO antigens with molecular typing for patients has not been reported.
  
  
  METHODS
  This study compared the historical RBC antigen phenotypes obtained by hemagglutination methods with genotype predictions in 494 patients with SCD. For discrepant results, repeat serologic testing was performed and/or investigated by gene sequencing for silent or variant alleles.
  
  
  RESULTS
  Seventy-one typing discrepancies were identified among 6360 antigen comparisons (1.1%). New specimens for repeat serologic testing were obtained for 66 discrepancies and retyping agreed with the genotype in 64 cases. One repeat Jk(b-) serologic phenotype, predicted Jk(b+) by genotype, was found by direct sequencing of JK to be a silenced allele, and one N typing discrepancy remains under investigation. Fifteen false-negative serologic results were associated with alleles encoding weak antigens or single-dose Fy(b) expression.
  
  
  CONCLUSIONS
  DNA-based RBC typing provided improved accuracy and expanded information on RBC antigens compared to hemagglutination methods, leading to its implementation as the primary method for extended RBC typing for patients with SCD at our institution.
authors.affiliation: Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Jessica
authors.initials: J
authors.lastname: Casas
authors.affiliation: Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.|Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: David F
authors.initials: DF
authors.lastname: Friedman
authors.affiliation: Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Tannoa
authors.initials: T
authors.lastname: Jackson
authors.affiliation: Immunohematology and Genomics Laboratory, New York Blood Center, New York City, New York.
authors.forename: Sunitha
authors.initials: S
authors.lastname: Vege
authors.affiliation: Immunohematology and Genomics Laboratory, New York Blood Center, New York City, New York.
authors.forename: Connie M
authors.initials: CM
authors.lastname: Westhoff
authors.affiliation: Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Stella T
authors.initials: ST
authors.lastname: Chou
mesh_terms: D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood* / Q000453:epidemiology / Q000628:therapy; D001803:Blood Transfusion / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006650:Histocompatibility Testing / Q000379:methods*; D006801:Humans; D007223:Infant; D008297:Male; D058889:Molecular Typing; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies; D055815:Young Adult