The IPD-IMGT/HLA database (release 3.41.0) currently comprises 2737 HLA-DRB1 alleles. However, for most alleles (96%) only exons 2 and 3 have been reported. Furthermore, the 118 full-gene characterized alleles are not the most common ones but often represent recently discovered rare variants. This lack of complete sequence information for many common or well defined HLA-DRB1 alleles disrupts the advantage of NGS for HLA genotyping. Therefore, we initiated a project aiming for the full-gene characterization of all HLA-DRB1 alleles down to a frequency of 0.0001 in European populations.