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Immunohematology and Genetic Testing (red cells/leukocytes and platelets) - Molecular Diagnostics and Testing

(P-IG-40) RHD*DAU0 Variant in Sickle Cell Disease Patient Population: Further Evidence of Lack of Partial Phenotype

Sunday, October 26, 2025

12:00 PM - 1:00 PM PT

Presenting Author(s)

Monike A. M Oliveira, MS

PhD Candidate
Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
Osasco, Sao Paulo, Brazil

Background/Case Studies: The DAU allele cluster represents a major cause of variability of D antigen expression and alloimmunization in patients with Sickle Cell Disease (SCD). Although within the DAU cluster of alleles (DAU0-DAU15), DAU0 encodes normal D epitope expression and recent evidence demonstrated that anti-D reactivity in the plasma of transfused patients with DAU0 did not differ from patients with conventional RHD*01, DAU0 remains classified as partial D in ISBT allele tables. This study evaluated whether DAU0 is associated with elevated risk for anti-D in transfused patients with SCD from the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) cohort, helping to fill any data gaps.

Study

Design/Methods: This study analyzed whole genome sequencing (WGS) data from 2,626 individuals with SCD enrolled in the REDS-III Brazil SCD cohort. Participants were recruited between 2013 and 2015 from four major transfusion centers across six Brazilian cities. WGS was performed using Illumina platforms as part of the NHLBI TOPMed initiative. RH genotyping, including RHD variant detection, was conducted using bloodTyper, an automated tool designed to identify RBC and platelet antigens from WGS data. Data on transfusion history and alloimmunization were provided by each participating center.

Results/Findings: Among the 2,626 genotyped individuals, 424 (16.1%) carried at least one DAU0 allele. Most (80.0%, n=339/424) had been previously transfused, mainly episodically (n=305/339). Three DAU0 alleles were identified: RHD*DAU0 (94.2%, n=323), RHD*DAU0.01 (5.5%, n=19), and RHD*DAU0.02 (0.3%, n=1). Among the transfused patients with DAU0 variants (n=339), DAU0 was most frequently found in heterozygosity with RHD*01 alleles (52.8%), followed by heterozygosity with D-negative alleles (26.0%), and homozygosity for DAU0 (6.8%). Additionally, DAU0 was found in heterozygosity with other RHD variants (12.5%), most notably with RHD*DIIIc (3.2%). No anti-D development was detected in these transfused patients, with the exception of one individual that developed an anti-D, which was serologically classified as an autoantibody. This patient carried the RHD*DVII.1 allele in trans to DAU0 (Table).

Conclusions: These findings provide further support that DAU0 does not encode a partial D phenotype or elevated risk for anti-D production following transfusion, supporting its classification as a conventional RHD allele for clinical transfusion practice. Characterization of RH variants and their associated risk are key to refine transfusion strategies, reduce unnecessary use of Rh negative blood and to guide application of RH genotype matching.