RHD alleles among pregnant women with serologic discrepant weak D phenotypes from a multiethnic population and risk of alloimmunization

• Published in: Journal of clinical laboratory analysis 2018-01, Vol.32 (1), p.n/a
• Main Authors: Bub, Carolina Bonet, Aravechia, Maria Giselda, Costa, Thiago Henrique, Kutner, José Mauro, Castilho, Lilian
• Format: Article
• Language: English
• Subjects: Alleles; Blood Grouping and Crossmatching; Cohort Studies; D variants; Deoxyribonucleic acid; DNA; DNA sequencing; Female; Genetic analysis; genetic counseling; Genotype; Genotyping; Genotyping Techniques - methods; Health risk assessment; Humans; Isoimmunization; partial D; Polymerase Chain Reaction; Population genetics; Pregnancy; pregnant women; Rh Isoimmunization - immunology; Rh Isoimmunization - prevention & control; Rh-Hr Blood-Group System - genetics; Rh-Hr Blood-Group System - immunology; RHD alleles; Rho(D) Immune Globulin - immunology; weak D
• ISSN: 0887-8013; 1098-2825
• DOI: 10.1002/jcla.22221

Background A considerable number of RHD alleles responsible for weak and partial D phenotypes have been identified. Serologic determination of these phenotypes is often doubtful and makes genetic analysis of RHD gene highly desirable in transfusion recipients and pregnant women. We analyzed the RHD gene in a cohort of pregnant women with doubtful D phenotypes. Methods RHD genotyping was performed on 104 cases with D typing discrepancies or with history of serologic weak D phenotype. Laboratory‐developed DNA tests, RHD BeadChip (Bioarray Solutions, Immucor), and sequencing were used to identify the RHD alleles. Results Molecular analyses showed 23 of 104 (22%) pregnant women were RHD*weak D types 1, 2, or 3 and not at risk for anti‐D. Fifty‐one (49%) were RHD*weak partial 4.0, 6 RHD*weak D type 38 (6%), 1 RHD*weak D type 45 (1%), 1 RHD*weak D type 67 (1%), and potentially at risk for being alloimmunized and making anti‐D. Partial D was identified in 22 of 104 (21%) patients and definitively at risk for anti‐D. Discussion Appropriate classification of RhD phenotypes is recommended for correct indication of RhIG in pregnant women. However, the serologic distinction between RhD‐negative and RhD‐positive phenotypes is a difficult task in the case of D variants due to the variations in serologic testing. Our results show a great variability in RHD variant alleles in pregnant women from this population of high admixture. According to these results, 78% of these obstetric patients are at risk for anti‐D and candidates for RhIG.