Rh discrepancies are a problem during routine testing because of partial D or weak D phenotypes. Panels of monoclonal antibodies (MoAb) are being developed to identify D variants such as partial D and weak D when there are anomalous D typing results; however, molecular characterization offers a more specific classification of weak and partial D. The weak D and partial D phenotypes are caused by many different RHD alleles encoding aberrant D proteins, resulting in distinct serologic phenotypes and the possibility of anti-D immunization. We evaluated currently used serologic methods and reagents to detect and identify D variants and correlated the results with molecular analyses. A total of 306 blood samples from Brazilian blood donors and patients with discrepant results in routine D typing were analyzed. In total, 166 (54.2%) weak D, 136 (44.4%) partial D, 3 (1%) DEL, and 1 (0.3%) DHAR variants were identified. Among weak D samples, 76 weak D type 1 (45.8%), 75 weak D type 2 (45.2%), 13 weak D type 3 (7.8%), and 2 weak D type 5 (1.2%) alleles were found. Among the partial D samples, 49 type 4.0 weak partial D (36%), 9 DAR (6.6%), 24 DFR (17.6%), 6 DBT (4.4%), 1 DHMi (0.73%), 26 DVI (19%), 14 DVa (10.3%), 5 DIVb (3.7%), and 2 DVII (1.5%) were observed. Two samples identified as DEL by adsorption-elution were characterized by molecular analyses as RHD(IVS5-38DEL4) and one sample was characterized as RHD(K409K). One sample was characterized as DHAR, a CE variant positive with some monoclonal anti-D. Our results showed that the use of different methods and anti-D reagents in the serologic routine analysis revealed D variants that can be further investigated. Molecular methods can help to differentiate between partial D and weak D and to characterize the weak D types, providing additional information of value in the determind for the prevention of anti-D-related hemolytic disease of the fetus and newborn. Nation of D phenotypes. This distinction is important for optimized management of D- RBC units and for the prevention of anti-D-related hemolytic disease of the fetus and newborn.271611Avent, N.D., Reid, M.E., The Rh blood group system: a review [published correction appears in Blood 200095:2197] (2000) Blood, 95, pp. 375-387Westhoff, C.M., The structure and function of the Rh antigen complex (2007) Semin Hematol, 44, pp. 42-50Wagner, F.F., Gassner, C., Müller, T.H., Schönitzer, D., Schunter, F., Flegel, W., Molecular basis of weak D phenotypes (1999) Blood, 93, pp. 385-393Wagner, F.F., Frohmajer, A., Ladewig, B., Weak D alleles express distinct phenotypes (2000) Blood, 95, pp. 2699-2708Wagner, F.F., (1998) The RhesusBase. Department of Transfusion Medicine, , http://www.uni-ulm.de/~fwagner/RH/RB/, University Hospital, Ulm, Germany. Accessed March 11, 2011Müller, T.H., Wagner, F.F., Trockenbacher, A., PCR screening for common weak D types shows different distributions in three Central European populations (2001) Transfusion, 41, pp. 45-52Flegel, W.A., Wagner, F.F., Molecular biology of partial D and weak D. Implications for blood bank practice (2002) Clin Lab, 48, pp. 53-59Denomme, G.A., Wagner, F.F., Fernandes, B.J., Li, W., Flegel, W.A., Partial D, weak D types, and novel RHD alleles among 33 864 multiethnic patients: implications for anti-D alloimmunization and prevention (2005) Transfusion, 45, pp. 1554-1560Körmöczi, G.F., Gassner, C., Shao, C.P., Uchikawa, M., Legler, T.J., A comprehensive analysis of DEL types: partial DEL individuals are prone to anti-D alloimmunization (2005) Transfusion, 45, pp. 1561-1567Legler, T.J., Maas, J.H., Köhler, M., Sequencing: a new tool for decision making on transfusion therapy and provision of Rh prophylaxis (2001) Transfus Med, 11, pp. 383-388Denomme, G.A., Dake, L.R., Vilensky, D., Ramyar, L., Judd, W.J., Rh discrepancies caused by variable reactivity of partial and weak D types with different serologic techniques (2008) Transfusion, 48, pp. 473-478Flegel, W.A., Khul, S.R., Wagner, F.F., Primary anti-D immunization by weak D type 2 RBCs (2000) Transfusion, 40, pp. 428-434Mota, M., Fonseca, N.L., Rodrigues, A., Kutner, J.M., Castilho, L., Anti-D alloimmunization by weak D type 1 red blood cells with a very low antigen density (2005) Vox Sang, 88, pp. 130-135Flegel, W.A., How I manage donors and patients with a weak D phenotype (2006) Curr Opin Hematol, 13, pp. 476-483Flegel, W.A., Wagner, F.F., RHD epitope density profiles of RHD variant red cells analyzed by flow cytometry (1996) Transfus Clin Biol, 3, pp. 429-431Ansart-Pirenne, H., Asso-Bonnet, M., Le Pennec, P.-Y., Roussel, M., Patereau, C., Noizat-Pirenne, F., RhD variants in Caucasians: consequences for checking clinically relevant alleles (2004) Transfusion, 44, pp. 1282-1286Jones, J., Filbey, D., Selection of monoclonal antibodies for the identification of D variants: Ability to detect weak D and to split epD2, epD5 and epD6/7 (1996) Vox Sang, 70, pp. 173-179Castilho, L., Carvalho, T., Credidio, D., Pellegrino, J., RHD genotyping in blood donors with highly diverse ancestry phenotyped as D-negative (abstract) (2008) Transfusion, 48, pp. SP448188ASingleton, B.K., Green, C.A., Avent, N.D., The presence of an RHD pseudogene containing a 37 base pair duplication and a nonsense mutation in Africans with the Rh D-negative blood group phenotype (2000) Blood, 95, pp. 12-18Maaskant-van wijk, P.A., Faas, B.H., de Ruijter, J.A., Genotyping of RHD by multiplex polymerase chain reaction analysis of six RHD-specific exons [published correction appears in Transfusion 199939:546] (1998) Transfusion, 38, pp. 1015-1021Castilho, L., Rios, M., Rodrigues, A., Pellegrino Jr., J., Saad, S.T.O., Costa, F.F., High frequency of partial DIIIa and DAR alleles found in sickle cell disease patients suggests increased risk of alloimmunization to RhD (2005) Transfus Med, 15, pp. 49-55Garratty, G., Do we need to be more concerned about weak D antigens? (editorial) (2005) Transfusion, pp. 1547-155
