Human Leukocyte Antigen (HLA) Frequencies and 4-loci HLA Haplotype Frequencies in Southern Thailand

Objective: To determine the antigen and haplotype frequencies of human leukocyte antigen-A (HLA-A), -B, -DRB1, and -DQB1 in southern Thailand. Material and Methods: We retrospectively analyzed HLA typing data from patients treated at Songklanagarind Hospital between September 2004 and May 2023. In total, 629 patients with HLA-A and -B typing results were included, and HLA-DRB1 and -DQB1 data were available for 529 patients. Haplotype frequencies were determined in 55 patients with complete four-locus HLA typing data from at least two family members. Results: A total of 66 unique HLA antigens were identified across four loci (16 HLA-A, 30 HLA-B, 13 HLA-DR, and 7 HLA-DQ). The most common HLA-A antigens were A24 (25.4%), A11 (24.3%), and A2 (18.8%). The most common HLA-B antigens were B75 (11.6%), B35 (8.4%), and B58 (8.4%). For HLA class II, the highest frequencies of HLA-DR antigens were found in DR15 (23.6%), DR12 (18.4%), and DR7 (10.9%). HLA-DQ5 (33.9%), DQ7 (21.6%), and DQ6 (14.3%) were the most frequently detected HLA-DQ antigens. The most prevalent four-loci haplotype was A33-B44- DR7-DQ2 (4.6%). Conclusion: This study provides valuable insights into the HLA antigens and haplotype frequencies in southern Thailand. These findings serve as a foundational basis for future studies on disease associations, support transplantation services, and contribute to personalized medicine.