The RHD(1227G>A) DEL-associated allele is the most prevalent DEL allele in Australian D– blood donors with C+ and/or E+ phenotypes

Authors


  • We acknowledge the Australian government that fully funds the Australian Red Cross Blood Service for the provision of blood products and services to the Australian community.

Abstract

Background

Red blood cells (RBCs) with D antigen levels only detected by anti-D adsorption-elution and an antiglobulin test express a DEL phenotype. For two DEL types, including RHD(1227G>A), immunization of D– recipients has been reported. This study's aim was to measure the prevalence of DEL-associated RHD alleles in a cohort of Australian D– donors to develop a model to estimate alloimmunization risk.

Study Design and Methods

D–, C+ and/or E+ blood donors were screened for RHD exons using quantitative polymerase chain reaction. Donors with RHD signals were DEL phenotyped with MCAD6 anti-D. RHD alleles were characterized via single-nucleotide polymorphism array or sequencing. Extended DEL phenotyping was performed with an anti-D panel.

Results

Among 2027 donors, 39 carried RHD alleles that have been previously reported to associate with either the DEL or the weak D phenotype. An additional five donors carried previously unreported RHD alleles and exhibited the DEL phenotype: RHD(IVS2-2delA), RHD(IVS1+5G>C), RHD(ex9:del/CE), and RHD(ex8:del/CE) represented twice. In total, DEL/weak D–associated RHD alleles were detected in 44 of 2027 donors or 2.17% (95% confidence interval, 1.54%-2.81%). The RHD(1227G>A) DEL allele was the most frequent (n = 16). The risk of transfusing D– females not more than 40 years of age with an RHD(1227G>A) DEL RBC unit (when managed as D–) is estimated to be one in 149,109 transfusions (range, 100,680-294,490).

Conclusion

DEL/weak D–associated RHD alleles were found in 2.17% of Australian D–, C+ and/or E+ blood donors. This differs from previous European reports in that the clinically significant RHD(1227G>A) DEL allele is the most prevalent.

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