RHD alleles in Brazilian blood donors with weak D or D-negative phenotypes

Area of Science:

• Immunogenetics
• Transfusion Medicine
• Population Genetics

Background:

• The RhD gene is highly polymorphic, leading to various RhD variant phenotypes.
• Serologic methods have limitations in distinguishing normal D antigen from D variants.
• RHD genotyping offers a more precise method for RhD antigen characterization.

Purpose of the Study:

• Determine the phenotypic frequency of RhD and RhCE antigens in Brazilian blood donors.
• Investigate the RHD alleles present in donors with weak D or D- phenotypes.
• Assess the utility of RHD genotyping for improving transfusion safety.

Main Methods:

• Phenotyping of D, C, c, E, and e antigens in 2007 blood donors.
• RHD genotyping using polymerase chain reaction-sequence specific primers for D- samples.
• Analysis of RHD gene exon 10 and intron 4.
• Further characterization of weak D or D- samples with RHD gene using genotyping platforms and nucleotide sequencing.

Main Results:

• Phenotypic frequencies: 87.3% D+, 11.9% D-, 0.8% weak D.
• RHD gene detected in 9.2% of D- individuals.
• Five RHD alleles identified in phenotypically D- donors: RHDΨ, RHD-CE-D(s), RHD-CE-(2-9)-D, RHD/RHDΨ, RHDΨ/RHD-CE-D(s), and RHD-CE(2)-D.
• Common weak D types: 1, 3, 4.0/4.1, and 4.2 (DAR).

Conclusions:

• RHD genotyping is essential for characterizing RHD alleles in donors with weak D or D- phenotypes.
• This molecular approach is vital for enhancing transfusion safety in ethnically diverse populations.
• Accurate RhD antigen identification through RHD genotyping reduces risks associated with alloimmunization.