A new high-prevalence LW antigen detected by an antibody in an Indigenous Australian homozygous for LW*A c.309C>A variant

Is it anti-D or anti-LW? A brief synopsis of the biology of the LW blood group and the importance and differential laboratory methods to discriminate these specificities

INTRODUCTION

The anti-LW antigen is not considered clinically significant. Yet, it can cause some challenges in differentiating it from the anti-D antigen in pretransfusion testing.

METHODS

This case report discusses a 35-year-old patient with nonmalignant gastrointestinal complications who was identified as having anti-LW during pretransfusion testing. We provide a brief history of the LW system and discuss the laboratory methods used to distinguish anti-LW from anti-D.

RESULTS

The patient's prior workup revealed an O RhD-positive blood type and an antibody compatible with anti-D. Auto-control and direct antiglobulin testing with anti-immunoglobulin G were only weakly positive, but the elution was negative. Red blood cell genotyping did not show any RhD variant. Current workup showed the patient's plasma reacting with both RhD-positive and RhD-negative group O cord blood and not reacting with RhD-positive dithiothreitol-treated cells, confirming anti-LW specificity.

DISCUSSION

Clarifying an apparent confusion between a true anti-D and a mimicking anti-LW in pretransfusion blood bank testing remains the basis of providing clinically relevant component therapy. Understanding the basics of the LW Blood Group System serology is fundamental to appropriate problem solving.

Anti-LW masquerading as anti-D in a D+ patient

LWa, LWab, LWb, and LWEM are the four main antigens of the Landsteiner-Weiner (LW) blood group system. LW expression may be weakened during pregnancy and immune dysregulation, with the subsequent appearance of anti-LW. Here, we describe a case of an elderly male patient in whom transfusion of red blood cells (RBCs) became challenging because of the presence of anti-LW. A 61-year-old male patient presented with shortness of breath and a hemoglobin level of 7.0 g/dL, requiring RBC transfusions. Serologic workup of his blood sample showed his RBCs to be group A, D+, but his serum was incompatible with several group A, D+ donor RBC units. Antibody screening showed preferential reactivity with D+ panel RBCs that was abolished when using 0.2 M dithiothreitol-treated RBCs. The patient's serum did not react with known RBCs of Rhnull and LW(a-) phenotypes but reacted strongly with D+ and D- cord RBCs. The patient's sample was genotyped as LW*A/A (c.299A), consistent with the LW(a+b-) phenotype. Subsequent bone marrow examination showed B-lymphoproliferative disorder. The patient required RBC transfusion support because of his underlying disease. Transfusion of group A, D- RBCs was uneventful. The expression of LW in this patient was possibly weakened by his underlying disease, leading to the development of anti-LW. No complications were seen after multiple transfusions of group A, D- RBC units.

A cold case of hemolytic disease of the fetus and newborn resolved by genomic sequencing and population studies to define a new antigen in the Rh system

BACKGROUND

We report an obstetric case involving an RhD-positive woman who had developed a red blood cell (RBC) antibody that was not detected until after delivery of a newborn, who presented with a positive direct antiglobulin test result. Immunohematology studies suggested that the maternal antibody was directed against a low-prevalence antigen on the paternal and newborn RBCs.

RESULTS

Comprehensive blood group profiling by targeted exome sequencing revealed a novel nonsynonymous single nucleotide variant (SNV) RHCE c.486C>G (GenBank MZ326705) on the RHCE*Ce allele, for both the father and newborn. A subsequent genomic-based study to profile blood groups in an Indigenous Australian population revealed the same SNV in 2 of 247 individuals. Serology testing showed that the maternal antibody reacted specifically with RBCs from these two individuals.

DISCUSSION

The maternal antibody was directed against a novel antigen in the Rh blood group system arising from an RHCE c.486C>G variant on the RHCE*Ce allele linked to RHD*01. The variant predicts a p.Asn162Lys change on the RhCE protein and has been registered as the 56th antigen in the Rh system, ISBT RH 004063.

CONCLUSION

This antibody was of clinical significance, resulting in a mild to moderate hemolytic disease of the fetus and newborn (HDFN). In the past, the cause of such HDFN cases may have remained unresolved. Genomic sequencing combined with population studies now assists in resolving such cases. Further population studies have potential to inform the need to design population-specific red cell antibody typing panels for antibody screening in the Australian population.

Equity in blood transfusion precision services

BACKGROUND

Blood collection agencies are integrating precision medicine techniques to improve and individualise blood donor and recipient outcomes. These organisations have a role to play in ensuring equitable application of precision medicine technologies for both donors and transfusion recipients. BODY: Precision medicine techniques, including molecular genetic testing and next generation sequencing, have been integrated in transfusion services to improve blood typing and matching with the aim to reduce a variety of known transfusion complications. Internationally, priorities in transfusion research have aimed to optimise services through the use of precision medicine technologies and consider alternative uses of genomic information to personalise transfusion experiences for both recipients and donors. This has included focusing on the use of genomics when matching blood products for transfusion recipients, to personalise a blood donor's donation type or frequency, and longitudinal donor research utilising blood donor biobanks.

CONCLUSION

Equity in precision services and research must be of highest importance for blood collection agencies to maintain public trust, especially when these organisations rely on volunteer donors to provide transfusion services. The investment in implementing equitable precision medicine services, including development of blood donor biobanks, has the potential to optimise and personalise services for both blood donors and transfusion recipients.