Introduction: Numerous studies have concentrated on specific populations to explore the extensive polymorphism of class I and II HLA genes. This genetic diversity is crucial for various applications, such as advancing transplantation immunology, understanding genetic population patterns, and uncovering the pathways of different diseases. Objective: The objective of the present study was to determine and analyse the frequencies of class I (HLA-A, HLA-B and, HLA-C), and class II (HLA-DRB1, and HLA-DQB1) genes in the North Indian population. Material and Methods: To achieve the objective of the study, buccal swab samples from 3648 individuals were collected. All these samples were subsequently tested for the HLA-A, HLA-B, HLA-C, HLA-DRB1, and HLA-DQB1 genes using the polymerase chain reaction (PCR) sequence-specific oligonucleotide probe (SSOP) typing method and typing result were analyzed to estimate class I and II allele frequencies. Results: In the present study, we have identified 16 different variants of HLA-A genes, 28 variants of HLA-B genes, 13 variations of HLA-C genes, 14 variants of HLA-DRB1 genes, and 6 variants of HLA-DQB1 genes. Furthermore, HLA-A*11, HLA-B*35, HLA-C*07, HLA-DRB1*15, and DQB1*06 were observed to be the most frequent alleles within the studied population. Discussion & Conclusions: The findings of the studied population highlight the variability exhibited by the HLA-A, HLA-B, HLA-C, HLA-DRB1, and HLA-DQB1 genes in the North Indian population. Additionally, this also highlights the importance of testing and understanding the prevalence of these specific HLA genes in these populations, which has a greater relevance in both hematopoietic stem cell and solid organ transplantation as well as disease association studies.

Background/Objectives: Epitope-based matching has emerged as a refined approach for assessing donor–recipient compatibility in renal transplantation. However, limited data are available on HLA Class I epitope distribution among Indian patients, particularly from northern India, where substantial allelic diversity is known to influence immunological risk. Methods: This retrospective analysis evaluated HLA Class I single-antigen bead (SAB) antibody data from 218 consecutive renal-transplant candidates who tested positive for anti-HLA antibodies between July 2018 and September 2024. HLA Class I epitopes were identified and analyzed using MATCH IT Antibody Software (Immucor, version 1.5.0). Demographic variables and sensitization history (previous transplant, transfusion, pregnancy) were reviewed. Results: A total of 504 distinct epitopes were identified, with 65GK and 163LG emerging as the most frequent motifs. The predominance of these epitopes mirrors the high prevalence of alleles such as HLA-A*24 and HLA-B*35 reported in North-Indian populations. The data suggest a strong influence of regional allele architecture on the immunogenic epitope landscape. Conclusions: This study provides the first baseline characterization of HLA Class I epitope distribution among northern-Indian renal-transplant candidates. The findings emphasize the need for establishing population-specific HLA epitope databases and highlight the potential of epitope-based matching to enhance donor selection and minimize immunological risk in Indian transplantation programs.