Molecular red cell genotyping of rare blood donors in South Africa to enhance rare donor-patient blood matching.

Lavendri Govender,Pavitra Pillay,Ute Jentsch,Rosaley D Prakashchandra

doi:10.4102/ajlm.v10i1.1400

Lavendri Govender, Pavitra Pillay + Show 2 more

Open Access

https://doi.org/10.4102/ajlm.v10i1.1400

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Abstract

BackgroundMolecular red cell genotyping is devoid of serology limitations such as the scarcity of rare antisera and the possibility of inconclusive results due to biological interferences. Blood incompatibility can result in immune transfusion reactions such as haemolytic transfusion reactions or haemolytic disease of the foetus and newborn.ObjectiveThe study aimed to use molecular red cell genotyping to identify rare blood group donors among South African blood donors.MethodsRed cell genotyping data were extracted retrospectively from the BIDS XT genotyping software in the Immunohaematology Reference Laboratory from January 2015 to August 2016. The ID CORE XT genotyping assay was used to identify the single nucleotide polymorphisms of 10 blood groups system alleles in 150 donors. Associations between the resultant genotypes and predicted phenotypes, ABO group, RhD type, race group and gender were studied.ResultsSignificant red cell genetic variability was noted among the numerous South African donor genotypes identified in this study. Genotyping further confirmed the presence of at least one of the 16 rare genotypes in 50 donors. Group O Black donors were associated with two rare blood types, while several other rare blood types were found only in White donors, supporting an association between ABO/Rh subtype, race group and rare blood types.ConclusionTargeted screening of donors for antigen-negative rare blood units for patients should be done to reduce the risk of haemolytic transfusion reactions and haemolytic disease of the foetus and newborn.

Highlights

The antigens found on the surface of red blood cells determine the blood type of an individual
This study aimed to provide the first comprehensive red cell genotyping of rare blood donors referred to the South African National Blood Service, Immunohaematology Reference Laboratory (IRL)
The 2015–2016 red cell genotyping data was skewed by a selection bias for Group O+ (71%, n = 107) donors which accounted for 33 rare blood types found in 32 donors

Summary

Introduction

The antigens found on the surface of red blood cells determine the blood type of an individual. Inconclusive serology results may result due to the interference from donor red blood cells in chronically transfused patients, a rare blood type causing false-positive results or autoantibodies in patients with autoimmune diseases.[5] sourcing blood for patients with rare blood types is challenging due to the scarcity of commercial rare antisera for serological testing.[6] The term rare blood type describes the absence of an antigen that is found normally in 99% of the country’s population and is described as: ‘negative for highfrequency-antigens (HFA)’ or the presence of antigens found in only 1% of the population termed ‘positive for low-frequency-antigens’ or the presence of an unusual or rare Rh subtype in a very small percentage of the population (1:1000, 1:10 000).[7] rare commercial antisera are often not readily available and are expensive. Blood incompatibility can result in immune transfusion reactions such as haemolytic transfusion reactions or haemolytic disease of the foetus and newborn

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