HLA allele and haplotype frequencies of eight Indian populations based on 130,518 registered stem cell donors

In hematopoietic stem cell transplantation, optimal results are achieved when donors and patients are matched regarding their human leukocyte antigen (HLA) genes. Population-specific HLA allele and haplotype frequency distributions determine the probabilities to find matched donors in a stem cell donor registry of given size and ethnic composition.

To evaluate the needs of Indian patients with regard to future donor recruitment, we analyzed a large data set of n=130,518 potential stem cell donors registered with DKMS-BMST, a Bangalore-based donor registry with nationwide donor recruitment activities. We defined 8 subpopulations by native language and state of origin of both parents. The subpopulations comprised four samples belonging to the Dravidian language family (native language: Kannada/state of origin: Karnataka, Tamil/Tamil Nadu, Telugu/Andhra Pradesh and Malayalam/Kerala), and four samples belonging to the Indo-Aryan language group (Bengali/West Bengal, Gujarati/Gujarat, Hindi/Uttar Pradesh, Marathi/Maharashtra). The precise definition of subpopulations and large sample sizes between n=5,808 (Telugu/Andhra Pradesh) and n=14,866 (Malayalam/Kerala) are strengths of our study. Our results regarding HLA allele and haplotype frequencies refine published data.

In terms of genetic relatedness, we observed a division of the subpopulations into a Southern and a Northwestern Indian cluster and the Bengali/West Bengal sample which differed significantly from the seven other subpopulations. Patients from Southern Indian populations are the main beneficiaries from the DKMS-BMST registry in the current ethnic composition. A more even nationwide coverage will be achieved in the future with the opening of local recruitment offices in different parts of India.