Background: The provision of compatible blood products to patients is the most essential task of transfusion medicine. Besides ABO and Rh, a number of additional blood group antigens often have to be considered for the blood supply of immunized or chronically transfused patients. It also applies for platelet antigens (HPA) and neutrophil antigens (HNA) for patients receiving platelet or granulocyte concentrates. Here, we describe the molecular screening for a number of blood group, HPA, and HNA alleles. Based on the screening results we are building up a regional blood donor registry to provide extended matched blood products on demand. Methods: We developed and validated TaqMan™ PCR and PCR-SSP methods for genetic markers defining 37 clinically relevant blood group antigens (beyond ABO and Rh), 10 HPA, and 11 HNA. Furthermore, we describe a feasible method for fast molecular screening of the HNA-2^null phenotype. All data were statistically evaluated regarding genotype distribution. Allele frequencies were compared to ExAC data from non-Finnish Europeans. Results: Up to now more than 2,000 non-selected regular blood donors in south-west Germany have been screened for blood group, HPA, and HNA alleles. The screening results were confirmed by serology and PCR-SSP methods for selected numbers of samples. The allele frequencies were similar to non-finnish Europeans in the ExAC database except for the alleles encoding the S, HPA-3b and HNA-4b antigens, with significantly lower prevalence in our cohort, as well as the LU14 and the HNA-3b antigens, with a higher frequency compared to the ExAC data. We identified 71 donors with rare blood groups such as Lu(a+b-), Kp(a+b-), Fy(a-b-) and Vel-, and 169 donors with less prevalent HPA or HNA types. Conclusion: Molecular screening for blood group alleles by using TaqMan™ PCR is an effective and reliable high-throughput method for establishing a rare donor registry.

Background: The detection and identification of antibodies to red blood cell (RBC) antigens is one of the most important and challenging issues in transfusion medicine. Up to date there are 354 RBC antigens recognized by the International Society of Blood Transfusion (ISBT). The reagent RBCs used in commercial antibody screening and identification panels however are usually serologically typed for up to 40 clinically important antigens. Thus the identification of many antibody specificities remains impossible when using reagent RBCs with only limited information about their antigens. To improve the pre-transfusion diagnostics, we developed antibody identification panels with reagent RBCs serologically typed for 26 antigens and additionally genotyped for 30 blood group alleles. Methods: The reagent RBCs in the panels were characterized serologically for the clinically most significant ‘standard' antigens. The reagent RBC donors were additionally genotyped by using in-house PCR-SSP methods. The antibody identification was performed in the indirect antiglobulin test using untreated and papain-treated RBCs in the gel technique. Antibodies identified due to the genotype information were confirmed by serology using appropriate reference RBCs. Results: Within a time period of 3 years and 8 months, 16,878 blood samples from 8,467 patients were tested in our reference laboratory. In total, 21 different antibodies from 10 different blood group systems could be identified in 126 patients (1.5%) due to the genotype information obtained for the reagent RBCs. Antibodies to antigens from the Knops system (53 patients; 42%, 8 patients with anti-Kn^b) and to Cartwright antigens (31 patients; 25%) were the most frequent. Conclusion: The use of genotyped reagent RBCs in antibody identification panels extends the range of detectable antibody specificities, accelerates the antibody identification, and improves the pre-transfusion diagnostics.