Abstract
Human leukocyte antigen (HLA) allele and haplotype frequency distribution varies widely between different ethnicities and geographical areas. Matching for HLA alleles is essential for successful related and unrelated stem cell transplantation. Among the Saudi population, data on HLA alleles and haplotypes are limited. A cross-sectional study was performed on 28,927 bone marrow donors. The most frequent HLA alleles were HLA-A*02:01:01G (20.2%), A*24:02:01G (7.5%); B*51:01:01G (19.0%), B*50:01:01G (12.3%); C*06:02:01G (16.7%), C*07:02:01G (12.2%); DRB1*07:01:01 (15.7%), DRB1*03:01:01G (13.3%); DQB1*02:01:01G (29.9%), DQB1*03:02:01G (13.2%); and DPB1*04:01:01G (35.2%), DPB1*02:01:02G (21.8%). The most frequent HLA-A similar to C similar to B similar to DRB1 similar to DQB1 haplotypes were A*02:01:01G similar to C*06:02:01G similar to B*50:01:01G similar to DRB1*07:01:01G similar to DQB1*02:01:01G (1.9%) and A*02:05:01G similar to C*06:02:01G similar to B*50:01:01G similar to DRB1*07:01:01G similar to DQB1*02:01:01G (1.6%). The most frequent HLA-A similar to C similar to B similar to DRB1 similar to DQB1 similar to DPB1 haplotypes were A*02:01:01G similar to C*15:02:01G similar to B*51:01:01G similar to DRB1*04:02 similar to DQB1*03:02:01G similar to DPB1*04:01:0G (1%) and A*02:01:01G similar to C*07:02:01G similar to B*07:02:01G similar to DRB1*15:01:01G similar to DQB1*06:02:01G similar to DPB1*04:01:01G (0.9%). Based on these haplotype frequencies, we provide forecasts for the fraction of patients with full matching and single mismatched donors for 3 to 6 loci depending on the registry size. With one million donors, about 50% of the patients would find an 8/8 match and 90% a 7/8 match. These data are essential for registry planning, finding unrelated stem cell donors, population genetic studies, and HLA disease associations.