RHD variants in Flanders, Belgium.

Area of Science:

• Immunohematology
• Molecular Biology
• Genetics

Background:

• D antigen variants (partial D, weak D, DEL) present diagnostic challenges.
• Accurate identification of D variants is critical for transfusion safety.
• Prevalence of D variants can be significant in certain populations.

Purpose of the Study:

• To evaluate the effectiveness of weak D genotyping for identifying D variants.
• To characterize the types and frequencies of D variants in the Flanders region of Belgium.
• To assess the clinical relevance of rapid D variant identification.

Main Methods:

• Genotyping of 628 samples with ambiguous serologic results using a commercial weak D typing kit.
• Molecular RHD exon scanning for samples negative for detectable weak D types.
• RHD sequencing for specific cases.

Main Results:

• 424 samples (67.5%) were positive for weak D Types 1, 2, or 3.
• 22 cases (3.5%) were identified as weak D Type 4.0/4.1/4.3, 4.2, 5, 11, 15, or 17.
• 49 samples (7.8%) were partial D variants, including 27 DVI types. A novel DVI Type 3 (A399T) was identified.

Conclusions:

• First-line weak D genotyping efficiently classified most D variants in Flanders.
• The study highlights the diversity of RHD alleles and their clinical significance.
• Rapid molecular methods are valuable for managing complex RhD phenotypes.