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Published on: January 17, 2018
Novel weak D types 31 and 32: adsorption-elution-supported D antigen analysis and comparison to prevalent weak D
Günther F Körmöczi1, Elisabeth Förstemann, Christian Gabriel
1Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria. guenther.koermoeczi@meduniwien.ac.at
Background:
Weak D types are thought to express rather quantitative than qualitative D antigen variants. Distinct type-specific phenotypes and weak D cases with anti-D alloimmunization, however, suggest a variable degree of D antigen alteration.
Study Design And Methods:
Variant D types were investigated by use of molecular typing, RHD sequencing, extended serologic D antigen investigations, and flow cytometric D antigen density determination.
Results:
Two novel weak D types were discovered, termed weak D type 31 and 32 with single RHD nucleotide substitutions coding for amino acid exchanges in predicted intracellular RhD polypeptide stretches, with antigen densities of approximately 130 and 50 D sites per red blood cell, respectively. Adsorption-elution technique-supported D epitope mapping of these two weak D types, the recently described weak D type 26, and of the most common Central European weak D types (weak D types 1, 2, 3, 4.0, and 4.1) demonstrated the expression of all tested D epitopes. In contrast, a distinct D epitope loss was detected in weak D type 15 and partial D control samples.
Conclusion:
All novel and prevalent weak D types expressed all tested D epitopes. Our results indicate that adsorption-elution techniques may be of advantage whenever D epitope loss is suspected in extremely weak D variants.
