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Three molecular structures cause rhesus D category VI phenotypes with distinct immunohematologic features
F F Wagner1, C Gassner, T H Muller
1Abteilung Transfusionsmedizin, Universitat Ulm and DRK-Blutspendezentrale Ulm, Ulm, Germany.
Blood
|April 16, 1998
Summary
Rhesus D category VI (DVI) is a significant partial D type. This study identifies new DVI genotypes and demonstrates at least three independent molecular origins for the DVI phenotype, impacting clinical diagnostics.
Area of Science:
- * Hematology
- * Genetics
- * Immunology
Background:
- * Rhesus D category VI (DVI) is the most clinically significant partial D antigen.
- * Previous understanding attributed DVI to two RHD-CE-D hybrid alleles with low RhD antigen density.
Purpose of the Study:
- * To investigate the molecular basis and population distribution of DVI in central Europe.
- * To characterize novel DVI genotypes and their genetic origins.
Main Methods:
- * Screening of three central European populations for DVI.
- * Exon-specific RHD polymerase chain reaction with sequence-specific primers (PCR-SSP) for genotyping.
- * cDNA sequencing, intron sequencing (introns 1, 2, 5, 6), and PCR-restriction fragment length polymorphism (PCR-RFLP) for detailed molecular characterization.
- * Flow cytometry and RhD epitope density profiling for immunohematologic analysis.
Main Results:
- * Twenty-six DVI samples were identified and analyzed.
- * A new genotype, D category VI type III, was characterized as a RHD-Ce(3-6)-D hybrid allele.
- * Distinct 3' breakpoints were identified for all known DVI types, and distinct 5' breakpoints for DVI type I and II.
- * The DVI phenotype arises from at least three independent molecular events.
- * Immunohematologic features and RhD protein surface density varied significantly among DVI types (DVI type III: ~12,000 antigens/cell; DVI type I: 500; DVI type II: 2,400).
- * DVI types were associated with specific haplotypes (DVI type II and III with CDe; DVI type I with cDE).
- * Significant variations in DVI type distribution were observed across the studied populations.
Conclusions:
- * The DVI phenotype has multiple independent molecular origins, highlighting allelic diversity in partial RhD.
- * Genotyping strategies must account for these variations for accurate clinical assessment.
- * Revisiting serologic and clinical data in light of molecular findings is crucial for understanding partial D antigen behavior.