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Ramsey G, Barriteau CM. Estimating the serological underrecognition of patients with weak or partial RHD variants. Transfusion 2024; 64:920-928. [PMID: 38634174 DOI: 10.1111/trf.17810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 03/05/2024] [Accepted: 03/14/2024] [Indexed: 04/19/2024]
Abstract
BACKGROUND For patients with weak or discrepant RhD RBC phenotypes, RHD genotyping is employed to determine need for RhD-negative management. However, many RHD variants are type D-negative or D-positive. Serological recognition rates (RRs) of weak and partial RHD variants are poorly characterized. STUDY DESIGN AND METHODS Four US studies employing RHD genotyping for weak or discrepant RhD phenotypes provided data for race/ethnicity-specific serological recognition. Three studies used microplate, and 1 used gel and tube; 2 had anti-D data. We obtained White and Hispanic/Latino allele frequencies (AFs) of weak D types 1, 2, and 3 single-nucleotide variants (SNVs) from the Genome Aggregation Database (gnomAD, v4.0.0) and devised Hardy-Weinberg-based formulas to correct for gnomAD's overcount of hemizygous RHD SNVs as homozygous. We compiled common partial RHD AF from genotyped cohorts of US Black or sickle cell disease subjects. From variant AF, we calculated hemizygous-plus-homozygous genetic prevalences. Serological prevalence: genetic prevalence ratios yielded serological RRs. RESULTS Overall RRs of weak D types 1-3 were 17% (95% confidence interval 12%-24%) in Whites and 12% (5%-27%) in Hispanics/Latinos. For eight partial RHD variants in Blacks, overall RR was 11% (8%-14%). However, DAR RR was 80% (38%-156%). Compared to microplate, gel-tube recognition was higher for type 2 and DAU5 and lower for type 4.0. Anti-D was present in 6% of recognized partial RHD cases, but only in 0.7% of estimated total genetic cases. DISCUSSION Based on AF, >80% of patients with weak or partial RHD variants were unrecognized serologically. Although overall anti-D rates were low, better detection of partial RHD variants is desirable.
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Affiliation(s)
- Glenn Ramsey
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Blood Bank, Northwestern Memorial Hospital, Chicago, Illinois, USA
| | - Christina M Barriteau
- Division of Hematology and Oncology, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Blood Bank, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
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Ramsey G, Park YA, Eder AF, Bobr A, Karafin MS, Karp JK, King KE, Pagano MB, Schwartz J, Szczepiorkowski ZM, Souers RJ, Thomas L, Delaney M. Obstetric and Newborn Weak D-Phenotype RBC Testing and Rh Immune Globulin Management Recommendations: Lessons From a Blinded Specimen-Testing Survey of 81 Transfusion Services. Arch Pathol Lab Med 2023; 147:71-78. [PMID: 35486492 DOI: 10.5858/arpa.2021-0250-cp] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 12/31/2022]
Abstract
CONTEXT.— Modern RHD genotyping can be used to determine when patients with serologic weak D phenotypes have RHD gene variants at risk for anti-D alloimmunization. However, serologic testing, RhD interpretations, and laboratory management of these patients are quite variable. OBJECTIVE.— To obtain interlaboratory comparisons of serologic testing, RhD interpretations, Rh immune globulin (RhIG) management, fetomaternal hemorrhage testing, and RHD genotyping for weak D-reactive specimens. DESIGN.— We devised an educational exercise in which 81 transfusion services supporting obstetrics performed tube-method RhD typing on 2 unknown red blood cell challenge specimens identified as (1) maternal and (2) newborn. Both specimens were from the same weak D-reactive donor. The exercise revealed how participants responded to these different clinical situations. RESULTS.— Of reporting laboratories, 14% (11 of 80) obtained discrepant immediate-spin reactions on the 2 specimens. Nine different reporting terms were used to interpret weak D-reactive maternal RhD types to obstetricians. In laboratories obtaining negative maternal immediate-spin reactions, 28% (16 of 57) performed unwarranted antiglobulin testing, sometimes leading to recommendations against giving RhIG. To screen for excess fetomaternal hemorrhage after a weak D-reactive newborn, 47% (34 of 73) of reporting laboratories would have employed a contraindicated fetal rosette test, risking false-negative results and inadequate RhIG coverage. Sixty percent (44 of 73) of laboratories would obtain RHD genotyping in some or all cases. CONCLUSIONS.— For obstetric and neonatal patients with serologic weak D phenotypes, we found several critical problems in transfusion service laboratory practices. We provide recommendations for appropriate testing, consistent immunohematologic terminology, and RHD genotype-guided management of Rh immune globulin therapy and RBC transfusions.
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Affiliation(s)
- Glenn Ramsey
- From the Department of Pathology, Northwestern University, Chicago, Illinois (Ramsey)
| | - Yara A Park
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill (Park)
| | - Anne F Eder
- Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland (Eder)
| | - Aleh Bobr
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota (Bobr).,Bobr is currently located in the Department of Pathology and Microbiology, at the University of Nebraska Medical Center, Omaha. Karafin is currently located in the Department of Pathology and Laboratory Medicine, at the University of North Carolina, Chapel Hill. Schwartz is currently located in the Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | | | - Julie K Karp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (Karp)
| | - Karen E King
- Department of Pathology, Johns Hopkins University, Baltimore, Maryland (King)
| | - Monica B Pagano
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle (Pagano)
| | - Joseph Schwartz
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York (Schwartz)
| | - Zbigniew M Szczepiorkowski
- Department of Pathology and Laboratory Medicine, Dartmouth College, Hanover, New Hampshire (Szczepiorkowski)
| | - Rhona J Souers
- Department of Biostatistics (Souers), College of American Pathologists, Northfield, Illinois
| | - Lamont Thomas
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (Karp).,Department of Proficiency Testing (Thomas), College of American Pathologists, Northfield, Illinois
| | - Meghan Delaney
- The Division of Pathology & Laboratory Medicine, Children's National Hospital, and the Departments of Pathology & Pediatrics, The George Washington University School of Medicine & Health Sciences, Washington, DC (Delaney)
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Barriteau CM, Lindholm PF, Hartman K, Sumugod RD, Ramsey G. RHD genotyping to resolve weak and discrepant RhD patient phenotypes. Transfusion 2022; 62:2194-2199. [PMID: 36218305 PMCID: PMC9828470 DOI: 10.1111/trf.17145] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 08/08/2022] [Accepted: 08/21/2022] [Indexed: 01/12/2023]
Abstract
BACKGROUND We instituted RHD genotyping in our transfusion service for obstetrical patients and transfusion candidates. We sought to examine how RHD genotyping resolved weak or discrepant automated microplate direct agglutination (MDA) RhD phenotypings and impacted needs for Rh Immune Globulin (RhIG) and D-negative RBCs. STUDY DESIGN AND METHODS We investigated RhD phenotypes with equivocal or reagent-discrepant automated MDA (Immucor, Norcross, GA), weak-2+ immediate-spin tube typings, historically discrepant RhD typings, or D+ typings with anti-D. We performed microarray RHD genotyping (RHD BeadChip, Immucor BioArray Solutions, Warren, NJ). Patients were managed as D+ with weak-D types 1, 2, and 3, and as D-negative with all other results. RESULTS Our weak-D prevalence was 0.14%. Among 138 patients (73 obstetrics, 65 transfusion candidates), 38% had weak-D types 1, 2 or 3, 25% weak partial type 4.0, 21% other partial-D variant alleles, and 15% no variant detected. One novel allele with weak partial type 4.0 variants plus c.150T>C (Val50Val) was discovered. Weak D types 1, 2 or 3 were identified in 66% (48/73) of Whites versus 3% (2/62) of diverse ethnic patients (p < .0001). RHD genotyping changed RhD management in 60 patients (43%) (49 to D+, 11 to D-negative), resulting in net conservation of D-negative RBCs (98 avoided, 14 given) and RhIG (8 avoided, 3 given). CONCLUSION In our patient population, equivocal or reagent-discrepant MDA RhD phenotypes were highly specific for weak-D or partial-D RHD genotypes. Resolution of RHD genotype status reduced our use of D-negative RBCs and RhIG.
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Affiliation(s)
- Christina M. Barriteau
- Division of Hematology and Oncology, Department of PediatricsFeinberg School of Medicine, Northwestern UniversityChicagoIllinoisUSA,Department of PathologyFeinberg School of Medicine, Northwestern UniversityChicagoIllinoisUSA,Blood Bank, Ann and Robert H. Lurie Children's Hospital of ChicagoChicagoIllinoisUSA
| | - Paul F. Lindholm
- Department of PathologyFeinberg School of Medicine, Northwestern UniversityChicagoIllinoisUSA,Blood Bank, Northwestern Memorial HospitalChicagoIllinoisUSA
| | - Karyn Hartman
- Blood Bank, Northwestern Central DuPage HospitalWinfieldIllinoisUSA
| | | | - Glenn Ramsey
- Department of PathologyFeinberg School of Medicine, Northwestern UniversityChicagoIllinoisUSA,Blood Bank, Northwestern Memorial HospitalChicagoIllinoisUSA
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