Characterization of Novel RHD Allele Variants and Their Implications for Routine Blood Group Diagnostics

Area of Science:

• Immunology
• Genetics
• Transfusion Medicine

Background:

• The Rh blood group system, particularly the D antigen, is crucial in transfusion medicine due to its high immunogenicity.
• Variant RhD phenotypes, arising from numerous RHD gene alleles, can lead to hemolytic transfusion reactions and hemolytic disease of the fetus and newborn.
• Accurate blood group diagnostics are essential for ensuring safe transfusion therapy.

Purpose of the Study:

• To characterize the phenotypes of four individuals with weakened D expression identified during routine pre-transfusion testing.
• To identify and analyze novel RHD alleles associated with weak D or partial D phenotypes.

Main Methods:

• Serological typing using standard gel card matrix techniques with monoclonal and polyclonal anti-D antibodies.
• D epitope and antigen density analysis.
• Genotyping via PCR with sequence-specific primers, genomic and allele-specific Sanger sequencing, and in silico protein analysis.

Main Results:

• Identification of four novel RHD alleles associated with weak D or partial D phenotypes.
• One mutation predicted to disrupt the stop codon, leading to an elongated D protein with a loss of D epitopes.
• Description of a hybrid RHD-RHCE gene.

Conclusions:

• The identified novel RHD alleles contribute to the understanding of RhD variant phenotypes.
• These findings enhance the knowledge of the Rh system.
• The study may facilitate advancements in blood group diagnostics for transfusion safety.