HLA allele and haplotype frequencies in a subset of 456 Turkish patients in the blood and bone marrow donor registry of Istanbul Medical Faculty

Abstract

Determining the HLA‐matched donor is the primary goal in searching donors for successful allogeneic hematopoietic stem cell transplantation (HSCT). In this study, the aim was toevaluate the differences in HLA haplotype frequencies of patients who received HSCT from unrelated donor and who has not yet found a potential donor in one year. Four hundredfifty‐six Turkish patients having been searched for unrelated donors between 2019‐2020 were included in the study. While 123 of these patients are being transplanted, 333 of themare waiting for HLA matched unrelated donors. We identified 95 class‐I, 45 class‐II HLA alleles that are common in patients transplanted from an HLA‐matched unrelated donor.A*02:01, B*51:01, C*04:01, DRB1*15:01, DQB1*03:01 were the most frequent alleles at each locus. Haplotype estimation of the 123 transplanted patients analyzed 3 different 5‐locus‐haplotypes are A*01:01, B*37:01, C*06:02, DRB1*04:01, DQB1*03:02 (0.8%); A*24:02, B*51:01, C*16:02, DRB1*15:01, DQB1*06:02 (0.8%); A*02:01, B*18:01, C*12:03, DRB1*11:04, DQB1*03:01 (0,6%).We identified 118 class‐I, 57 class‐II HLA alleles that are common in patients who are still waiting for potential donors. A*24:02, B*51:01, C*04:01, DRB1*11:04, DQB1*03:01 were the most frequent alleles at each locus. Haplotype estimation of the 333 patients analyzed 3 different 5‐locus‐haplotypes are A*11:01, B*51:06, C*14:02, DRB1*15:01, DQB1*06:01 (0.4%); A*01:01, B*13:02, C*06:02, DRB1*07:01, DQB1*02:02 (0.3%); A*02:01, B*18:01, C*07:01, DRB1*11:04, DQB1*03:01 (0.3%). The haplotype analyzes in the HSCT waiting list might be useful to predict the potential donor availability for Turkish patients. The Knowledge of the most frequent haplotypes should also be used to describe strategies to optimize donor searches.