Xunda Luo1, Margaret A Keller2, Ian James1, Michelle Grant1, Shiguang Liu1, Kellie Simmons Massey1, Andrew Czulewicz3, Sandra Nance2,4, Yanhua Li5. 1. Department of Pathology and Laboratory Medicine, Temple University Hospital, Temple University, Philadelphia, PA, United States of America. 2. American Red Cross, Temple University, Philadelphia, PA, United States of America. 3. Department of Pathology, Jeanes Hospital, Temple University, Philadelphia, PA, United States of America. 4. University of Pennsylvania, Department of Pathology and Laboratory Medicine, Division of Transfusion Medicine, Temple University, Philadelphia, PA, United States of America. 5. Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States of America.
Abstract
BACKGROUND: RhD variants have altered D epitopes and/or decreased antigen copies per red cell. Individuals carrying these variants may test antigen negative, weakly positive, or positive by serology, and may or may not be at risk of alloimmunisation after exposure. There have been recommendations to perform RHD genotyping of patients, pregnant women and females of childbearing potential with serological weak D phenotype, to guide prophylactic use of Rh immune globulin (RhIG), and better conserve D-negative blood products. The purpose of this study was to evaluate the performance of a set of empirical criteria to identify such patients. MATERIALS AND METHODS: A two-method strategy of gel testing (GT) and tube testing (TT) was used for Rh typing of patients with no historical blood type in the present institution. A monoclonal-polyclonal blend anti-D was used for Rh typing by TT at immediate spin. Three empirical criteria were used to identify candidates for genotyping: C1: discrepancy between the two test methods and a GT reaction strength >2+ stronger than TT; C2: weak serological reaction, defined as reaction strength ≤2+ regardless of testing method if both GT and TT were performed or reaction strength ≤2+ if only GT was performed, or reaction strength ≤1+ if only TT was performed; C3: presence of anti-D in D-positive patients with no history of RhIG use in the preceding 3 months and in whom alloanti-D is suspected. RESULTS: Overall, 50 patients, ranging from newly born to 93 years old, were identified. Genomic testing confirmed D variants in 49/50 cases with a positive predictive value of 98%. DISCUSSION: This two-method strategy is a powerful screening tool for identifying candidates for RHD genotyping. This strategy meets the current requirements of two blood type determinations/two specimens in pre-transfusion testing while simultaneously identifying candidates for RHD genotyping with a minimal increase in work load and cost.
BACKGROUND:RhD variants have altered D epitopes and/or decreased antigen copies per red cell. Individuals carrying these variants may test antigen negative, weakly positive, or positive by serology, and may or may not be at risk of alloimmunisation after exposure. There have been recommendations to perform RHD genotyping of patients, pregnant women and females of childbearing potential with serological weak D phenotype, to guide prophylactic use of Rh immune globulin (RhIG), and better conserve D-negative blood products. The purpose of this study was to evaluate the performance of a set of empirical criteria to identify such patients. MATERIALS AND METHODS: A two-method strategy of gel testing (GT) and tube testing (TT) was used for Rh typing of patients with no historical blood type in the present institution. A monoclonal-polyclonal blend anti-D was used for Rh typing by TT at immediate spin. Three empirical criteria were used to identify candidates for genotyping: C1: discrepancy between the two test methods and a GT reaction strength >2+ stronger than TT; C2: weak serological reaction, defined as reaction strength ≤2+ regardless of testing method if both GT and TT were performed or reaction strength ≤2+ if only GT was performed, or reaction strength ≤1+ if only TT was performed; C3: presence of anti-D in D-positive patients with no history of RhIG use in the preceding 3 months and in whom alloanti-D is suspected. RESULTS: Overall, 50 patients, ranging from newly born to 93 years old, were identified. Genomic testing confirmed D variants in 49/50 cases with a positive predictive value of 98%. DISCUSSION: This two-method strategy is a powerful screening tool for identifying candidates for RHD genotyping. This strategy meets the current requirements of two blood type determinations/two specimens in pre-transfusion testing while simultaneously identifying candidates for RHD genotyping with a minimal increase in work load and cost.
Authors: F F Wagner; A Frohmajer; B Ladewig; N I Eicher; C B Lonicer; T H Müller; M H Siegel; W A Flegel Journal: Blood Date: 2000-04-15 Impact factor: 22.113
Authors: H Okuda; H Suganuma; T Kamesaki; M Kumada; N Tsudo; T Omi; S Iwamoto; E Kajii Journal: Biochem Biophys Res Commun Date: 2000-08-11 Impact factor: 3.575
Authors: S Gerald Sandler; Willy A Flegel; Connie M Westhoff; Gregory A Denomme; Meghan Delaney; Margaret A Keller; Susan T Johnson; Louis Katz; John T Queenan; Ralph R Vassallo; Clayton D Simon Journal: Transfusion Date: 2014-12-01 Impact factor: 3.157
Authors: Willy A Flegel; Gregory A Denomme; John T Queenan; Susan T Johnson; Margaret A Keller; Connie M Westhoff; Louis M Katz; Meghan Delaney; Ralph R Vassallo; Clayton D Simon; S Gerald Sandler Journal: Transfusion Date: 2020-03-12 Impact factor: 3.337