Hemolytic disease of the newborn caused by anti-Wright (anti-Wra): case report and review of literature

Genetic prediction of 33 blood group phenotypes using an existing genotype dataset

BACKGROUND

Accurate blood type data are essential for blood bank management, but due to costs, few of 43 blood group systems are routinely determined in Danish blood banks. However, a more comprehensive dataset of blood types is useful in scenarios such as rare blood type allocation. We aimed to investigate the viability and accuracy of predicting blood types by leveraging an existing dataset of imputed genotypes for two cohorts of approximately 90,000 each (Danish Blood Donor Study and Copenhagen Biobank) and present a more comprehensive overview of blood types for our Danish donor cohort.

STUDY DESIGN AND METHODS

Blood types were predicted from genome array data using known variant determinants. Prediction accuracy was confirmed by comparing with preexisting serological blood types. The Vel blood group was used to test the viability of using genetic prediction to narrow down the list of candidate donors with rare blood types.

RESULTS

Predicted phenotypes showed a high balanced accuracy >99.5% in most cases: A, B, C/c, Coa /Cob , Doa /Dob , E/e, Jka /Jkb , Kna /Knb , Kpa /Kpb , M/N, S/s, Sda , Se, and Yta /Ytb , while some performed slightly worse: Fya /Fyb , K/k, Lua /Lub , and Vel ~99%-98% and CW and P1 ~96%. Genetic prediction identified 70 potential Vel negatives in our cohort, 64 of whom were confirmed correct using polymerase chain reaction (negative predictive value: 91.5%).

DISCUSSION

High genetic prediction accuracy in most blood groups demonstrated the viability of generating blood types using preexisting genotype data at no cost and successfully narrowed the pool of potential individuals with the rare Vel-negative phenotype from 180,000 to 70.

Immunohematological testing and transfusion management of the prenatal patient

The primary indication for immunohematological testing in the prenatal patient is to detect and identify maternal red cell antibodies. If there are antibodies that are expected to hemolyze the fetus' red cells, their strength of reactivity must be tested, and the fetus' antigen status determined. After delivery, testing is performed to assess the extent of fetomaternal hemorrhage, as a large hemorrhage may require other therapeutic interventions. Another major role for immunohematological testing is to select blood components appropriately when intrauterine transfusion is required for fetal anemia resulting from maternal alloimmunization or some other cause. Supplementation with molecular methods has transformed the practice of immunohematology, particularly as it applies to typing for the D antigen of the Rh blood group system. Notwithstanding the advances in testing, close coordination and communication between the transfusion service and the obstetrics service are the foundation for ensuring the finest care for prenatal patients, and for new mothers and their infants. This review describes testing and transfusion practices for prenatal patients, using case presentations to highlight the management of selected immunohematological findings. It also includes a discussion of key patient management topics that are currently unresolved.

Acute hemolytic reaction by anti-Wra: Case report and review of the hemovigilance database of a tertiary care hospital

Wra is the most common LIA in white population. The incidence of Wra antigen in Spanish population has been estimated to be 1 in 785 in blood donors, while anti-Wra was found in 2.7 % and 3.6 % of healthy donors and transfused patients respectively. Severe, even fatal hemolytic transfusion reactions and hemolytic disease of the newborn caused by anti-Wra have been reported. Since the reagent red blood cells used for antibody screening usually lack Wra antigen, the anti-Wra is not detected and hemolytic reaction could occur if transfusion is performed by type and screen approach. We report an acute hemolytic reaction due to anti-Wra in a patient with negative antibody screening. We have also reviewed the records of the hospital hemovigilance database in order to collect the previous hemolytic cases due to anti-Wra. During a 21-year period 461,539 red blood cell units have been transfused to 81,614 patients in our hospital. Alloimmnunization was detected in 3840 patients (0.83 %) and anti-Wra was detected in 22 patients (1/3709), 10 of whom had other alloantibodies, and only in 1 occasion (this case) has been implicated in mild hemolytic acute transfusion reaction. In our experience, the risk of fatal hemolytic reaction due to LIA in hospitals with blood services using the type and screen policy is extremely low.

A fatal case of acute hemolytic transfusion reaction caused by anti-Wra: case report and review of the literature

The red blood cell (RBC) antigen Wr^a is a low-prevalence antigen first described in 1953 by Holman and assigned to the Diego system in 1995. Because of its low prevalence, Wr^a is usually absent on commercial screening RBCs and antibody identification panels. When Wr(a+) screening RBCs are available, the corresponding antibody, anti-Wr^a, is often found in sera from healthy individuals, patients, and pregnant women. Anti-Wr^a can cause both hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. We describe a fatal acute hemolytic transfusion reaction caused by anti-Wr^a in a patient with no other RBC alloantibodies. Serologic investigation showed that one of the RBC units the patient received was Wr(a+). Immunohematology 2021;37:20-24.

The red blood cell (RBC) antigen Wr^a is a low-prevalence antigen first described in 1953 by Holman and assigned to the Diego system in 1995. Because of its low prevalence, Wr^a is usually absent on commercial screening RBCs and antibody identification panels. When Wr(a+) screening RBCs are available, the corresponding antibody, anti-Wr^a, is often found in sera from healthy individuals, patients, and pregnant women. Anti-Wr^a can cause both hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. We describe a fatal acute hemolytic transfusion reaction caused by anti-Wr^a in a patient with no other RBC alloantibodies. Serologic investigation showed that one of the RBC units the patient received was Wr(a+). Immunohematology 2021;37:20–24.

Fatal Acute Hemolytic Transfusion Reaction due to Anti-Wra

Background

The Wr^a blood group antigen is a low-frequency antigen. Antibody screening sets used in pretransfusion laboratory investigations usually do not contain a Wr(a+) cell. If subsequent cross-matching is performed without indirect antiglobulin test (IAT), Wr^a antibodies reacting with donor red blood cells (RBCs) will be missed. For reasonable economic and time-saving arguments the risk of missing the detection of a potential clinically relevant antibody is worldwide accepted.

Case Report

A 66-year-old women with a negative antibody screen rapidly deteriorated after she received two units of RBCs for symptomatic anemia after hip surgery. Diagnosis of a transfusion reaction was obscured by pre-existing and nonspecific symptoms. Laboratory investigation indicated acute hemolysis. Cross-matching in IAT was positive for the first unit, and an extended antibody identification panel showed reactivity with Wr(a+) cells. The patient did not respond to supportive therapy and died within 48 h after the start of transfusion.

Conclusion

This dramatic case provides further evidence on the clinical relevance of Wr^a blood group antibodies. In addition, it underlines the clinical importance of risk awareness in the blood transfusion chain and the possible complexity in relation to patient monitoring in daily transfusion practice.

Transient Porphyrinemia in a Neonate: A Case Report

We describe a neonate with anemia, thrombocytopenia, and hyperbilirubinemia secondary to hemolytic disease of the newborn. After phototherapy for hyperbilirubinemia, the neonate developed a photodistributed eruption with high serum and urine porphyrin levels. This transient porphyrinemia resolved at 1 month.

How to use: the direct antiglobulin test in newborns

The direct antiglobulin test (DAT) detects the presence of immunoglobulin, complement or both bound to the red blood cell membrane. The test, historically called the 'Coombs test', was first described in 1945 by Cambridge immunologist Robin Coombs. Suspected haemolytic disease of the newborn, due to either Rhesus disease or ABO incompatibility, is one of most common reasons for requesting a DAT in newborns. In this article, we discuss the physiological background and technological background of the DAT. We also provide a clinical framework for a rational approach to the use and interpretation of the DAT in newborns.