HLA

About HLA / Human leukocyte antigen:

HLA - or human leukocyte antigen - is a set of genes that encodes for proteins on cells’ surfaces that regulate the function of the immune system. The human version of the gene complex is the analogue to the animal version of the MHC (major histocompatibility complex class).

HLA Functions
HLAs are implicated in a range of functions in the human body. For instance, in infectious diseases, certain immune cells break down antigen-presenting cells via phagocytosis and break them into small pieces. HLAs antigens are then displayed to CD4+ helper T cells when then create the various effects to eliminate the pathogen.
In autoimmunity, HLA types are associated with certain autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, and celiac disease. Now that researchers more fully understand HLA types, it is becoming easier for them to diagnose specific diseases, such as type 1 diabetes and celiac.

Human leukocyte antigen Classification
Researchers segment HLA into three major MHC subgroups: HLA-A, HLA-B,, and HLA-C - as well as some minor genes.

HLA Structure
HLA loci, like many MHC loci across mammals, have highly variable genetic coding. Over the eons, HLA loci survived the constriction with resulting high variable structures. HLA loci are among the fastest-evolving in the human genome. Many remote tribes isolated from the global population have undergone profound gene conversion between the loci and alleles within each HLA gene class.
In total, six loci have more than 100 alleles detected across the total human population. Currently, the most variable is HLA-B and HLA DRB1. The high variability of HLA genes makes it difficult to study their role in disease.