The HLA (human leucocyte antigen) system encodes the major histocompatibility complex (MHC) proteins in humans. These integral cell membrane glycoproteins are responsible for the regulation of the human immune system. There are two classes of MHC, i.e., MHC class I and MHC class II. The HLA gene complex is located on a 3.6 Mb region within chromosome 6p21. They are the most polymorphic gene family found in the human genome, with more than 10,000 different HLA alleles reported to date, thus the capacity to mount an immune response can be dramatically different between individuals within a cohort selected from a single population. HLA genes have been strongly implicated in transplant rejection, autoimmune disease, vaccine pharmacogenomics, cancer, infectious diseases, and mate selection.
HLA genotyping is the identification of the HLA class I and class II gene polymorphisms for individuals, which is indispensable for transplant matching and disease association studies. Unambiguous HLA genotyping is technically challenging owing to high polymorphism in various genomic regions. The development of NGS has changed this landscape of genotyping. High-resolution HLA genotyping by using PCR and NGS is uniquely able to address limitations of traditional HLA genotyping and Sanger sequencing assays in patients. It enables robust, simple, high-quality, and high-throughput analysis of the key HLA genes, data can be phased to a minimum of 6 digits. Another advantage is that phasing problem is determined since DNA templates are derived from single molecules.
