The Human Leukocyte Antigen (HLA) system is a series of major histocompatibility complex (MHC) proteins in humans. They are cell-surface proteins that play important roles in the immune system in humans. Studies have demonstrated that HLA is critical for disease defense, protection from cancers, organ transplant rejections. In addition, HLA can be potential biomarkers of susceptibility to some diseases or drug adverse reactions. 11 HLA types of major MHC complexes are exhibited in Fig.1. HLA is highly polymorphic, thus investigating the polymorphism is necessary and challenging. Learn more: HLA mapping