Two Prevalent ∼100-kb GYPB Deletions Causative of the GPB-Deficient Blood Group MNS Phenotype S-s-U- in Black Africans.

The U antigen (MNS5) is one of 49 antigens belonging to the MNS blood group system (ISBT002) carried on glycophorins A (GPA) and B (GPB). U is present on the red blood cells in almost all Europeans and Asians but absent in approximately 1.0% of Black Africans. U negativity coincides with negativity for S (MNS3) and s (MNS4) on GPB, thus be called S-s-U-, and is thought to arise from homozygous deletion of GYPB. Little is known about the molecular background of these deletions. Bioinformatic analysis of the 1000 Genomes Project data revealed several candidate regions with apparent deletions in GYPB. Highly specific Gap-PCRs, only resulting in positive amplification from DNAs with deletions present, allowed for the exact genetic localization of 3 different breakpoints; 110.24- and 103.26-kb deletions were proven to be the most frequent in Black Americans and Africans. Among 157 CEPH DNAs, deletions in 6 out of 8 African ethnicities were present. Allele frequencies of the deletions within African ethnicities varied greatly and reached a cumulative 23.3% among the Mbuti Pygmy people from the Congo. Similar observations were made for U+var alleles, known to cause strongly reduced GPB expression. The 110- and 103-kb deletional GYPB haplotypes were found to represent the most prevalent hereditary factors causative of the MNS blood group phenotype S-s-U-. Respective GYPB deletions are now accessible by molecular detection of homo- and hemizygous transmission.

Fetal inheritance of GP*Mur causing severe HDFN in an unrecognized case of maternal alloimmunization.

BACKGROUND: The clinical and laboratory features of hemolytic disease of the newborn can be challenging to diagnose during pregnancy in the apparent absence of a blood group antibody. Low-frequency antibodies go undetected due to the lack of appropriate antigen-positive reagent red blood cells (RBCs). CASE REPORT: A pregnant woman of Southeast Asian descent was referred to a maternal-fetal medicine outpatient clinic due to a complicated obstetric history and a negative antibody screen. This initial visit at 29 weeks and 0 days' gestational age (GA) was unremarkable. A hydropic infant, born at 29 weeks and 5 days' GA, succumbed on the seventh day of life. Comprehensive laboratory testing was performed after birth. The hospital blood bank performed a maternal antibody identification. Direct antiglobulin test was performed on the cord blood. A reference laboratory confirmed an anti-Mia , performed paternal Mia phenotyping, and identified a hybrid glycophorin B-A-B GP*Mur allele. DISCUSSION: Maternal alloimmunization to low-frequency antigens remains a challenge. Southeast Asians make up a significant percentage in some US locations. Worldwide reports on the frequency of maternal alloimmunization of the MNS system can be used to guide the use of specific reagent RBCs for testing. Such strategies rely on the identification of blood donor units for reagent manufacture and use in perinatal antibody screens. CONCLUSION: The incidence of Mia and related antibodies is significant among Southeast Asians. In North America, prenatal antibody screening cells are not routinely chosen to match this population. The clinical and societal implications are discussed.

Use of a cloud-based search engine of a centralized donor database to identify historical antigen-negative units in hospital inventories.

BACKGROUND: The provision of units with antigen-negative attributes is required for alloimmunized transfusion recipients and to avoid alloimmunization among patients on chronic transfusion support. Recent evidence confirms that the demand for antigen-typed units is increasing. STUDY DESIGN AND METHODS: A cloud-based search engine was designed by the blood center to find antigen-negative units. The service provided access to historical antigen information for units in hospital inventories. The hospital transfusion service was required to confirm the antigen phenotype. The results of 16 hospitals' use over 5 years were analyzed to determine trends and value of the service. The time commitment of the cloud-based query was compared to the hospital performing manual phenotyping with an outcome of at least one unit found with the desired antigen-negative attribute(s). RESULTS: Hospitals were located between 4 miles and 200 miles away from the blood center. A total of 6,081 queries were submitted over the 5 years, with an overall 50% success rate of finding at least one unit. Single antigen queries accounted for 67% of total searches, with two antigen queries and three or more antigen queries accounting for 24% and 9% of the units found, respectively. The cloud-based antigen query was most efficient for combined antigen frequencies <0.5 for two or more antigen-negative attributes. CONCLUSION: A cloud-based search engine provides hospitals with access to historical antigen information housed at the blood center. Future refinements may consider regulatory submission of a process to provide confirmed historical information through this cloud-based program.

Acute autoimmune hemolytic anemia due to anti-Ena autoantibody successfully treated with rituximab.

BACKGROUND: Autoimmune hemolytic anemia (AIHA) due to anti-Ena has been previously reported in association with massive intravascular hemolysis, disseminated intravascular coagulation, and fatal outcomes. Here we report a case of successfully treated AIHA due to anti-Ena . CASE REPORT: A 69-year-old male with a past medical history of cirrhosis due to nonalcoholic steatohepatitis status post-orthotopic liver transplant presented with 1-month history of progressive anemia. At presentation, his hemoglobin (Hb) was 5.6 g/dL, hematocrit (Hct) 16%, reticulocytes 0.3%, direct bilirubin (bili) 4 g/dL, lactate dehydrogenase 533 units/L (reference, 125-220 units/L), and haptoglobin 254 mg/dL (reference, 40-273 mg/dL). Blood bank testing revealed an autoantibody present in his plasma and a direct antiglobulin test positive for immunoglobulin G (IgC) but negative for complement. He received 1 unit of an incompatible blood group O phenotypically matched red blood cell unit. RESULTS: Over the course of the next 5 days, the Hb and Hct decreased to 4.1 g/dL and 12%, respectively, direct bili increased to 12.3 mg/day, reticulocytes slightly increased to 0.9%, and haptoglobin decreased to less than 8 mg/dL. Marrow study showed a hypercellular marrow with erythroid hyperplasia. Additional workup performed at a reference laboratory identified an anti-Ena autoantibody. He received prednisone and weekly rituximab infusions and was monitored weekly. At the 2-month visit, Hb and Hct were 10 g/dL and 32%, respectively. CONCLUSION: Unlike two of the previously reported fatal cases of AIHA with anti-Ena specificity, this 69-year-old male treated with weekly rituximab infusion underwent clinical recovery and significant anemia improvement.

Practical approaches and costs for provisioning safe transfusions during anti-CD38 therapy.

BACKGROUND: Anti-CD38 therapy causes interference with both the direct and the indirect antiglobulin tests. We describe the experience from an Immunohematology Reference Laboratory and model cost options for providing safe transfusions. STUDY DESIGN AND METHODS: Phenotyping, genotyping, and antibody identification orders were retrospectively reviewed in the setting of anti-CD38 therapy. The data were used to model the added cost of transfusion support. Four approaches were evaluated: 1) thiol-treated reagent red blood cells (RRCs) in antibody investigations with K- red blood cell (RBC) transfusions, 2) patient phenotyping or 3) genotyping with antigen-matched RBC transfusions, and 4) a combination of interval thiol-treated RRC antibody investigations with genotype antigen-matched RBC transfusions. RESULTS: Sixty-two patients were identified as receiving anti-CD38 therapy. Thiol-treated RRC antibody investigations (28/62 patients) were favored over genotyping (23/62) and combination testing (11/62). Patient phenotyping failed to detect useful antigen information on eight patients: seven Fyb silencing mutations and one partial e. A thiol-treated RRC antibody investigation was the least expensive testing method for the first transfusion, but four- and five-antigen-matched RBC transfusions were equal in cost within five and 21 transfusion events, respectively. CONCLUSION: Genotyping provided a more accurate antigen status than phenotyping patient RBCs. Patients requiring long-term transfusion support benefit from antigen matching when matching less than four antigens. Ultimately, the decision to genotype or use thiol-treated RRC antibody investigations will vary for each hospital blood bank.