Eurotransplant Reference Laboratory
Information about Virtual PRA Calculator
Virtual PRA Calculator.
Virtual PRA Calculator is an application to be used by professionals working in HLA Laboratories and other HLA specialists to define the percentage virtual Panel Reactive Antibodies (vPRA) within the Eurotransplant donor population.
The virtual PRA is calculated on basis of unacceptable antigens only. These antigens are defined by HLA antibody analysis from screenings for HLA specific, transplantation relevant antibodies. The calculation is currently performed for unacceptable antigens on HLA-A, -B, -C, -DR and -DQ.

Description of the underlying database.
Calculations are performed on the ETRL reference database v3.0, which contains HLA data of 10.000 deceased donors used for renal transplantation between 2012 and 2018 within the Eurotransplant area.
Donors with complete HLA typing for HLA-A, -B, -C, -DR and -DQ have been selected. Donors with missing HLA data for one or more loci were excluded after verification that the HLA antigens that were known from these donors were not significantly different from the HLA antigens of donors with complete HLA typing information.
All alleles are available at split antigen level, except B14 and Cw3. Bw4 and Bw6 are included in the database. In case of missing data, Bw4/Bw6 has been assigned based on HLA-B antigens only.
Please be aware that assigning a Bw4 will not include corresponding HLA-A antigens. HLA-A antigens harboring a Bw4 epitope need to be filled in separately.
Missing split alleles for HLA-DQ3 were imputed by using linkage information of HLA-DRB1.
Finally, DR51/52/53 are also included in the database. In case of missing data, imputation based on DRB1 typing was performed. DR53 has been removed for donors with DR7 and DQ9, because in this case DR53 is non-expressed.

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