DPB1*7601, a novel DPB1 variant in the Caucasoid population

Abstract: A new DPB1 allele has been identified in a Caucasoid individual, DPB1*7601. The sequence of the complete second exon has been confirmed by cloning and subsequent sequencing. This allele differs by one amino acid, at codon 36, from DPB1*1401, as indicated by SBT and PCR-SSP analysis. The amino-acid motif introduced by the change is shared by DPB1*0401 and some rare alleles. It remains unclear whether the change is due to interallelic microgen conversion or a single point mutation.     

DPB1*8501, a novel DPB1 variant in the US Black population

We describe a new DPB1 allele, DPB1*8501, which was identified by sequencing-based typing (SBT) in the UCLA exchange. DPB1*8501 is similar to DPB1*2701 with a difference at position 272, (G to A). This difference leads to an amino-acid change of codon 91 from arginine (CGC) to histidine (CAC). Until now this position has been considered conserved. This substitution is located at the 3' site of exon 2, and may interfere with typing strategies using primers or probes located in this region.     

Two new HLA DPB1 alleles identified by sequence-based typing: DPB1*8201 and DPB1*8301

Two new HLA DPB1 alleles were identified by sequence-based typing and are reported. Both alleles differ from DPB1*0402 by a single nucleotide: DPB1*8201 has a difference at position 359 (codon 91) leading to an amino acid change from arg to his, making this position a new polymorphic site; DPB1*8301 has a difference at position 280 (codon 65) changing the amino acid from ile to phe.     

New DRB1* alleles (HLA-DRB1*1135, DRB1*1430 and DRB1*1433) and a confirmatory sequence (DRB1*1133)

Three new DRB1 alleles (DRB1*1135, DRB1*1430 and DRB1*1433) and a confirmatory sequence (DRB1*1133) have been identified after following up unusual or novel polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) patterns during routine typing of the DRB1*03,*08,*11,*12,*13 and *14 allele groups. Of the new alleles found and described in this paper, two alleles were initially detected by the PCR-RFLP method which produced unexpected restriction polymorphism (DRB1*1133 and DRB1*1135) while the remaining two were found after following up rare allele typings from this technique (DRB1*1430 and DRB1*1433).     

Three new DPB1 alleles identified in a Bantu-speaking population from central Cameroon

HLA-DPB1 genotyping of 241 individuals from an African Bantu-speaking population in central Cameroon using sequence-specific oligonucleotide probes identified five individuals with novel probe hybridization patterns. DNA sequence analysis of the second exon of the DPB1 alleles from these five individuals identified three new alleles, *6001, *6101N, and *6201. DPB1*6001, found in two individuals, contains a single nucleotide change that results in a polar amino acid, asparagine, at residue 65; this position in the β1 domain is occupied by a nonpolar amino acid in all other reported DPB1 alleles. DPB1*6101N, found in one individual, contains a single base mutation that results in a premature termination codon at position 67. DPB1*6201, found in two individuals, is characterized by the apparent motif shuffling that has been hypothesized to be responsible for the majority of DPB1 sequence polymorphism. These new sequences shed additional light on the potential mechanisms by which allelic diversity is generated at the HLA-DPB1 locus.     

The nucleotide sequence of two new DP alleles, DPA1*02015 and DPB1*8401, identified in a Chinese subject

The HLA-DP genes (HLA-DPA1 and -DPB1) are encoded by the major histocompatibility complex (MHC) on human chromosome 6. They are involved in the presentation of antigen to CD4+ T cells as part of the class II antigen-presentation pathway. During a small study of Oriental subjects (11 Chinese and 26 Japanese subjects), one Chinese subject was identified as having numerous heterozygous sites within the second exon of both DPA1 and DPB1. These were further analysed using novel codon-specific primers. Sequencing analysis using these primers determined the subject to have DPA1*0103/*02015 and DPB1*0501/*8401; these new alleles have been submitted to GenBank and assigned the accession numbers AF098794 and AF077015, respectively.     

High resolution sequence-based DPB1 typing identified two novel DPB1 alleles,DPB1*9401 and DPB1*9501, from a Kenyan population

Two novel DPB1 alleles, DPB1*9401 and DPB1*9501, were identified from a Kenyan population during sequence-based HLA-DPB1 typing. Molecular cloning and sequencing of multiple clones confirmed that one of the new DPB1 alleles is identical to DPB1*0402 at exon 2 except for a single nucleotide substitution (CGG -->TGG), changing codon 70 from Arg to Trp. The new allele has been named DPB1*9401. This is the first report of polymorphism at codon 70 of HLA-DPB1 alleles. New codon combinations have been identified in another novel DPB1 allele named DPB1*9501. The extensive diversity at DPB1 locus of this East African population is being revealed by high resolution sequence-based DPB1 typing.     

Three new DP alleles identified in sub-Saharan Africa: DPB1*74O1, DPAl*02013, and DPAl*0302

Abstract: HLA-DP genotyping of over 400 individuals from sub-Saharan Africa identified three new DP alleles: DPB1*7401, DPAl*02013, and DPAl*0302. DNA sequencing confirmed that DPB1*7401, found in one individual, is a novel combination of previously described sequence motifs in the six variable regions of DPB1. DPA1*02013, found in one individual, is identical to DPAl*02012 except for two silent substitutions, a T to C transition in codon 37, and an A to G transition in codon 38. DPAl*0302, identified in seven individuals, is identical to DPAl*0301 except for a C to T transition at the second position of codon 66. The identification of these novel alleles brings the total number of reported DPB1 alleles to 77 and DPA1 alleles to 11.     

DPB1*8601, a previously unrecognized DPB1 variant in the Caucasoid population

A new, previously unrecognized DPB1* allele, DPB1*8601, was found in a Swedish family. The new allele was carried on the common North European haplotype HLA A1-B8-DR3. Both individuals carrying the new allele were initially typed as clear DPB1*4601,*6601 but after family studies and further typing with allele-specific primers it was concluded that a new allele was present together with the common DPB1*0401. The new allele was investigated by direct sequencing of exon 2 in both forward and reverse directions employing intron primers combined with either an allele-specific sense or anti-sense biotinylated primer for bi-directional sequencing. The new allele is identical to DPB1*1701 in the five first variable regions. In the sixth region, however, DPB1*8601 carries the GGPM motif shared by several common alleles such as DPB1*0201 and 0401and 0402.