HLAtypes

HLAtypes refer to the specific alleles of the human leukocyte antigen (HLA) gene complex that an individual carries. The HLA region, located on chromosome 6, encodes cell-surface proteins that present peptide fragments to T cells and thus shape immune recognition. HLA genes are divided into class I (HLA-A, -B, -C) and class II (HLA-DP, -DQ, -DR) loci. Each person inherits two haplotypes, one from each parent, yielding a characteristic HLA type for each locus. Collectively, a person’s HLA type is the combination of alleles across these loci.

HLA alleles are highly polymorphic, resulting in many possible HLA types in the human population. Alleles are named with the locus, an asterisk, and numeric codes (for example HLA-B*07:02). High-resolution typing specifies alleles to four-digit (or higher) precision, whereas lower resolution records two-digit groups.

Laboratory HLA typing uses serology or molecular methods. Molecular approaches include PCR-based sequence-specific oligonucleotide probing, sequence-specific priming, and sequencing-based typing, including next-generation sequencing. The choice of method influences resolution and ambiguity.

HLA types are central to transplantation. Matching donor and recipient HLA alleles reduces graft rejection risk, especially at HLA-A, -B, and -DR loci. They also influence susceptibility to certain autoimmune diseases and drug hypersensitivities, though a given HLA type is rarely determinative of disease. Population genetics studies emphasize broad diversity and regional haplotypes, which can complicate matching but inform transplantation strategies and disease association research.