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Heterogeneous molecular background of the weak C, VS+, hr B-, Hr B- phenotype in black persons

Bach-Nga Pham1, Thierry Peyrard, Genevieve Juszczak

  • 1Institut National de la Transfusion Sanguine, CNRGS-INSERM U665, Paris, France. bnpham@ints.fr

Transfusion
|December 2, 2008
PubMed

Insights

The rare Hr(B)- blood group phenotype arises from two distinct (C)ce(s) haplotypes in the Black population. Molecular investigation revealed genetic heterogeneity, impacting Rh antigen expression and necessitating genetic screening for blood donors.

Area of Science:

  • Hematology
  • Genetics
  • Immunology

Background:

  • The rare Hr(B)- blood group phenotype is associated with the homozygous (C)ce(s) haplotype.
  • This haplotype involves a hybrid RHD-CE-D(s) gene and a ce(s) allele of RHCE, with specific nucleotide substitutions.
  • Previous understanding of the (C)ce(s) haplotype's molecular basis required further investigation.

Purpose of the Study:

  • To investigate the molecular background of the (C)ce(s) haplotype.
  • To understand the genetic basis of the Hr(B)- phenotype in individuals of Black ancestry.

Main Methods:

  • Genomic DNA analysis of twelve individuals with depressed C and/or e antigens.
  • Identification of specific 733C>G and 1006G>T substitutions.
  • Analysis of Rh antigen expression and complete RHD/RHCE transcript sequences.

Main Results:

  • A novel hybrid RHD-CE-D(s) gene linked with a ce(s) allele was identified, similar to the classical (C)ce(s) haplotype.
  • Both haplotypes resulted in weak e, VS+, and absent D, V, hr(B), and Hr(B) antigens.
  • The new haplotype produced a weaker C antigen and lacked Rh42 expression compared to the classic haplotype.

Conclusions:

  • The molecular basis of the weak C, VS+, hr(B)-, Hr(B)- phenotype is heterogeneous in the Black population.
  • Two distinct (C)ce(s) haplotypes contribute to this phenotype.
  • Molecular characterization of Rh genes is crucial for screening blood donors with hr(B)- or Hr(B)- phenotypes.
Abstract

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