title: A simple diagnostic strategy for RhD typing in discrepant cases in the Indian population.
abstract: BACKGROUND
  The D antigen is the most immunogenic antigen in the Rh system. D variants must be considered if there is a significant discrepancy in the strength of reaction obtained with different anti-D reagents, a discrepancy between current and historical test results and if anti-D is detected in an individual serologically typed as RhD positive. A panel of monoclonal anti-D reagents can be used to identify partial D and weak D variants. The aim of this study was to develop a strategy for RhD typing in discrepant cases.
  
  
  METHODS
  Sixty RhD discrepant samples referred to our Institute for confirmation of RhD status were tested with a panel of 12 monoclonal anti-D reagents (ALBAclone advanced partial RhD typing kit) and Rh phenotype was determined using C, c, D, E, and e antisera.
  
  
  RESULTS
  Ninety-three percent of the RhD discrepant cases were classified into weak and partial D using this kit. Among the D variants characterised, 37% belonged to DFR, 23% to DOL, 12% to weak D, and the remaining 21% to DAR, DV, DMH, DCS and DVI categories. Ninety-seven percent of the D variants were "C" antigen positive. Out of the panel of 12 monoclonal anti-D used, cell line LHM-70/45 gave negative reactions with all RhD discrepant cases and cell lines LHM-76/59, LHM-76/55 and ESD-1 gave positive reactions with all 60 RhD discrepant cases studied.
  
  
  CONCLUSIONS
  The Advanced partial D kit was very useful in characterising and identifying D variants in the Indian population. A preliminary strategy for the detection and identification of D variants in discrepant cases could be to test for the presence of "C" antigen with anti-C, and for "D" antigen with anti-D of cell line LHM 70/45. A more comprehensive, but simple way to identify D variants in routine RhD typing is to use two anti-D reagents i.e LHM 70/45 and one out of LHM-76/59, LHM-76/55 and ESD-1. D variants can be further characterised by using the partial D typing kit and molecular genotyping in specialised laboratories.
authors.affiliation: Department of Transfusion Medicine, National Institute of Immunohaematology, ICMR, KEM Hospital Campus, Parel, Mumbai, India. swatiskulkarni@gmail.com
authors.forename: Swati
authors.initials: S
authors.lastname: Kulkarni
authors.forename: Vasantha
authors.initials: V
authors.lastname: Kasiviswanathan
authors.forename: Kanjaksha
authors.initials: K
authors.lastname: Ghosh
mesh_terms: D001788:Blood Grouping and Crossmatching / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000737:chemistry; D007194:India; D008297:Male; D011933:Reagent Kits, Diagnostic; D012204:Rh-Hr Blood-Group System
chemical_list: D007106:Immune Sera; D011933:Reagent Kits, Diagnostic; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen