New HLA-DR haplotypes containing the DRB6 pseudogene.

An unexpected probe reaction pattern was observed in two samples during HLA-DR typing by PCR-Sequence Specific Oligonucleotide Probes. In order to confirm the unusual typings, samples were analyzed by PCR-Sequence Specific Primers, cloning, and nucleotide sequencing of the second exon of the HLA-DRB-genes. The confirmed DR, DQ phenotype for one sample was DRB10701, DRB401, DRB50101, DRB60201, DQB0602, DQB10202. The phenotype of other sample was DRB11602, DRB11302, DRB30301, DRB60101, DQB10501, DQB10502. The first sample has the novel combination of DRB10701 with DRB50101 and DRB60201. The second sample has either DRB60101 together with DRB11602 in absence of any DRB5 allele or DRB60101 together with DRB11302, DRB30301. We postulate that the most likely haplotype in sample #1 is DRB10701; DRB50101, DRB10602 which could have arisen from gene conversion. The most likely haplotype in sample #2, DRB11602, DRB60101, DQB10502 would have arisen from an homologous recombination event.