title: Molecular basis of the rare gene complex, DIVa(C)-, which encodes four low-prevalence antigens in the Rh blood group system.
abstract: BACKGROUND
  Over 40 years ago, an unusual Rh phenotype denoted DIVa(C)- was identified in a case of fatal haemolytic disease of the newborn in the third child of Madame Nou. Her RBCs expressed a partial D, weak C and four low-prevalence Rh antigens: Go(a) (RH30), Rh33 (RH33), Riv (RH45) and FPTT (RH50). The purpose of this study was to determine the molecular basis associated with this rare DIVa(C)- complex.
  
  
  METHODS
  Blood samples were from three donors previously identified as carrying the DIVa(C)- haplotype. Molecular analyses were performed by standard methods.
  
  
  RESULTS
  The three donors were heterozygous for RHD and RHD*DIVa.2, and all carried a compound hybrid allele at the RHCE locus. This hybrid RHCE allele contained exons 2 and 3 from RHD*DIVa.2 and exon 5 from RHD [RHCE*CE-DIVa.2(2-3)-CE-D(5)-CE] and is in cis to RHD*DIVa.2. The RHCE allele on the in trans chromosome differs between the donors and is RHCE*cE in donor 1, RHCE*ce (254C, 733G) in donor 2 and RHCE*ce in donor 3.
  
  
  CONCLUSIONS
  The RHD*DIVa.2 encodes the Go(a) antigen, whereas the compound hybrid allele most likely encodes Rh33, Riv and FPTT. The weakly expressed C antigen on RBCs with the DIVa(C)- phenotype could be encoded by exons 2 and 3 from RHD*DIVa.2 in the compound hybrid. This is the first report of RHD*DIVa.2 being involved in a hybrid gene at the RHCE locus. As only one example of anti-Riv has been described, our molecular analysis and findings provide a tool by which to predict Riv expression.
authors: Laboratory of Immunochemistry, New York Blood Center, New York, NY, USA.
authors: C H
authors: CH
authors: Hipsky
authors: K
authors: K
authors: Hue-Roye
authors: C
authors: C
authors: Lomas-Francis
authors: C-H
authors: CH
authors: Huang
authors: M E
authors: ME
authors: Reid
mesh_terms: D001789:Blood Group Antigens / Q000235:genetics* / Q000276:immunology; D015321:Gene Rearrangement; D006801:Humans; D015995:Prevalence; D012204:Rh-Hr Blood-Group System / Q000235:genetics* / Q000276:immunology
chemical_list: D001789:Blood Group Antigens; D012204:Rh-Hr Blood-Group System