Profiling the genetic diversity of the HLA system in Mexico using 9-locus allele and haplotype frequencies from donors in the NMDP Mexico donor center

Profiling the HLA diversity at the population level benefits multiple clinical and anthropological applications, such as tracing population migration, identifying genetic relationships between different groups, quantifying the added diversity in a global donor pool and matching for solid organ and stem cell transplantation. We calculated nine-locus HLA-A ∼ C ∼ B ∼ DRB1 ∼ DRB3/4/5 ∼ DQA1 ∼ DQB1 ∼ DPA1 ∼ DPB1 allele and haplotype frequencies in about 170,000 volunteer donor genotypes from the NMDP Mexico (NMDP MX, previously Be The Match Mexico) donor center. These donors are predominantly of Mexican ancestry recruited from multiple regions in Mexico. The goal of the study was to describe the HLA genetic profiles of the Mexican population and investigate the contribution of these donors' HLA in serving Mexican, US and international patients in need of hematopoietic cell transplants. Additionally, we estimated that almost all Mexican patients will have an available 5 of 8 or better matched donor in the NMDP MX donor center with matches also available for some of the Latino patients in the U.S. We demonstrate that Mexican populations clustered genetically and shared multiple frequent alleles and haplotypes with populations from the US Mexican or Chicano, US South/Central American Hispanic, and some Latino populations. Operationally, 78 % of NMDP Mexico donors contributed genotypes that were observed a total of three times or less on the registry, increasing the diversity of the overall NMDP registry. More than 300 donor collections were facilitated through the NMDP MX donor center serving mostly Hispanic/Latino patients in the US and abroad. This study highlights the importance of adding the NMDP MX donors to the worldwide donor pool and paves the way for a data-driven strategy for future planning and donor recruitment.