engleski

IMPACT OF HLA-A~B~DRB1 HAPLOTYPE POLYMORPHISMS ON DONOR SELECTION IN HEMATOPOIETIC STEM CELL TRANSPLANTATION PROGRAM IN CROATIA

The duration and success rate of an unrelated donor search in hematopoietic stem cell transplantation greatly depends on patients’ HLA typing. Studies about HLA haplotype frequency in Croatian Bone Marrow Registry revealed 50 most frequent HLA-A~B~DRB1 haplotypes (>0.1%). The rest of them were defined as less frequent (<0.1%) or rare if they included at least one HLA allele observed three times at maximum in our population. The aim of the study was to analyze 362 patients transplanted with an unrelated donor from 2012 to 2017 in UHC Zagreb. All patients had family derived haplotypes. We investigated distribution of HLA haplotypes in order to evaluate the probability of finding a donor in the national or international registries. In the group of 73 patients (20.17%) who received a transplant from national donor (group 1), 92 different haplotypes were found while in the group of 289 patients (79.83%) who found an international donor (group 2), the diversity of haplotypes was much higher, 432 different haplotypes. HLAA* 01:01~B*08:01~DRB1*03:01 haplotype showed the highest frequency in both groups ; however, its presence was significantly higher in group 1 (18.49% and 2.94%, respectively ; P<0.0001). HLA genotypes consisting of two frequent haplotypes, as well as genotypes consisting of one frequent and one less frequent haplotype were significantly more present in group 1 than in group 2 (23.29% vs. 4.84%, P<0.0001 and 60.27% vs. 44.29%, P=0.0179, respectively). Genotypes with both less frequent haplotypes were significantly more observed in group 2 (47.06% vs. 15.09%, P<0.0001). The same states for the genotypes consisting of one less frequent and one rare haplotype, which we found in six patients with international donors and just one patient with a national donor. These data suggest that the presence of at least one frequent haplotype serves as a positive predictive factor for finding a donor in our registry while patients bearing less frequent or rare haplotype will mostly benefit from finding a donor worldwide.

HLA-A~B~DRB1 HAPLOTYPE, HSCT, Croatian population

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