HLA-A, -C, -B, and -DRB1 allelic and haplotypic diversity in bone marrow volunteer donors from Northern Portugal

Analysis of the HLA allelic and haplotype frequency data in different populations helps to shed light on the evolutionary factors that result in genetic polymorphism and the biological relationships among different ethnic groups. It is important to analyse HLA allele and haplotype frequencies in different populations to find compatible marrow transplantation donors from unrelated individuals. The aim of this study was to investigate the distribution of HLA-A, -C, -B and DRB1 alleles and haplotypes in Northern Portugal. The HLA-A, -C, -B, and -DRB1 allele frequencies were determined by direct counting. The haplotype frequencies were calculated using the expectation-maximisation algorithm in Arlequin v3 software. The Hardy-Weinberg equilibrium was verified using the Guo and Thompson method. The most frequent (> 10%) HLA-A alleles (A*02, A*01, A*03, and A*24), HLA-B alleles (B*44, and B*35) and HLA-C alleles (C*07, and C*04) found in this study frequently occur in many other Caucasian populations. Of the class II HLA alleles at the HLA-DRB1* locus, the allelic groups HLA-DRB1*07 and -DRB1*13 occur most frequently (> 15%) in the Portuguese population, as previously reported by others. The HLA-A*01-C*07-B*08-DRB1*03 and HLA-A*29-C*16-B*44-DRB1*07 haplotypes, described as being of Pan European and western European origin, respectively, were the most frequent haplotypes found in our sample, and they are very frequent in Caucasian Brazilian, German, Italian, Spanish and the previously described Portuguese populations. These data represent an important contribution to future anthropological and disease association studies involving the Portuguese population