title: HLA-B44 allele frequencies and haplotypic associations in three European populations.
abstract: HLA-B44 is among the most frequent class I antigens in many populations studied so far. It has been subdivided into seven allelic forms that can only be discriminated by DNA typing. Using a simple PCR/sequence-specific oligonucleotide hybridization procedure, we have analysed the frequency distribution of B44 subtypes in three European populations from Slovenia, the Netherlands, and Switzerland. B*4402 and B*4403 were by far the predominant alleles, B*4404 and 4405 were rare, while B*4406 and B*4407 were not observed. Interestingly, B*4402 and 4403 occurred with different frequencies in the three populations, with B*4402 being most frequent in the Swiss (65% vs. 57% in the Dutch, and 46.5% in the Slovenes). Of the 139 individuals studied, 60 HLA-B44 ABDR haplotypes could be determined by family studies. In the respective populations, the linkage disequilibria between B44 and other HLA antigens occurred with different frequencies. A2-B*4402 haplotypes were very frequent in the Swiss sample, mostly associated with DRB1*0101, 0401 and 1301. B*4402 was more often linked with non-A2 antigens in the Slovenes (predominantly A24, A28) than in the Swiss and the Dutch. The predominant association of B*4403 was with DR7: this haplotype was very frequent in the Swiss (82% of the B*4403 haplotypes), while lower frequencies were found in the Dutch (72%) and Slovenian (59%) populations. In the Swiss population, more than half of the B44-DR7 haplotypes were A23-B*4403-DR7 (53% of all B*4403 haplotypes). This haplotype was significantly less frequent in the Slovenian (6%) and in the Dutch (14%) populations. The second most frequent B*4403 haplotype in both the Swiss and Slovenes is the A29-B*4403-CW*1601-DR7 haplotype (17.6 and 29.4%, respectively). Concomitant with the increased frequency of B*4403 in the Slovenes, a higher diversity of non-DR7 B44 haplotypes was observed in this population (41% of all B*4403 haplotypes). HLA-B44 oligotyping analysis allowed us to detect B44-subtype incompatibilities in several AB-sero, DRB1/B3/B5-oligo matched unrelated bone marrow donor/patient combinations. The different frequency distributions of HLA-B44 haplotypes in the three populations analysed in this study argue in favour of local volunteer bone marrow donor recruitment. This might significantly improve the chance of finding a highly matched donor for patients with less frequent A-B-DRB1 haplotypes.
authors.affiliation: Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia.
authors.forename: B
authors.initials: B
authors.lastname: Vidan-Jeras
authors.forename: B
authors.initials: B
authors.lastname: Breur-Vriesendorp
authors.forename: M
authors.initials: M
authors.lastname: Bohinjec
authors.forename: M
authors.initials: M
authors.lastname: Jeannet
authors.forename: E
authors.initials: E
authors.lastname: Roosnek
authors.forename: J M
authors.initials: JM
authors.lastname: Tiercy
mesh_terms: D000483:Alleles; D001782:Blood Donors; D005787:Gene Frequency; D015234:HLA-A Antigens / Q000032:analysis / Q000235:genetics; D015235:HLA-B Antigens / Q000032:analysis / Q000145:classification / Q000235:genetics*; D059948:HLA-B44 Antigen; D006684:HLA-DR Antigens / Q000032:analysis / Q000235:genetics; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D015810:Linkage Disequilibrium; D009426:Netherlands; D017524:Slovenia; D013557:Switzerland; D014019:Tissue Donors; D044465:White People / Q000235:genetics
chemical_list: D015234:HLA-A Antigens; D015235:HLA-B Antigens; D059948:HLA-B44 Antigen; D006684:HLA-DR Antigens