HLA-DP genotyping with sequence-specific oligonucleotides can detected known sequence variations in the polymorphic segments of the DPB1 second exon. Since the allelic polymorphism of the 22 published alleles is based on recombination of sequence motifs from six variable regions, DPB1 typing depends on the reactivity pattern of many different probes rather than from typing with single allele-specific probes. By computer simulation, we have previously shown that the minimal set of probes to define the 22 different alleles and most of the heterozygous combinations is 18. Here we describe HLA-DPB1 typing results and allele frequencies in a panel of 200 unrelated Caucasians from Southwest Germany. The result confirmed the power of the new HLA-DPB1 typing method, but we failed to detect three of the previously described alleles in our panel. To accommodate with the observed 19 different alleles, the sequence and hybridization conditions of 17 oligonucleotide probes are given, which are able to differentiate all except two, resolved by group-specific amplification, of the 190 possible heterozygous phenotypes.
