Human Leukocyte Antigen (HLA) Typing by DNA Sequencing

DNA sequencing is a powerful technique for identifying allelic variation within the human leukocyte antigen (HLA) genes. Sequencing is usually focused on the most polymorphic exons of the class I (HLA-A, -B, -C) and class II (HLA-DR, -DQ, and -DP) genes. These exons encode the antigen recognition site, the region of the HLA molecule that binds peptides and interacts with the T cell receptor for antigen and natural killer cell immunoglobulin-like receptors (KIR). Sanger sequencing of amplified DNA from each HLA gene from a preparation containing one or two alleles yields a sequence that is used to identify the alleles by comparison with a reference database.