Library · Genetics
HLA system
Make it clearer
The HLA system, also called the human major histocompatibility complex, is a set of more than 200 genes devoted to immune defense. They all live together in the same place: the short arm of chromosome 6.
Two families of molecules arise from it. The class I molecules are encoded by three loci, the positions where a gene sits, called A, B and C. The class II molecules come from three others, DR, DQ and DP. And there is one detail that changes everything: these genes are codominant. Neither one wins out over the other; the allele that came from the father and the one that came from the mother are both expressed.
The chance that two people express identical molecules is extremely low. It is a molecular ID badge: almost no two people carry the same combination. And when HLA molecules are recognized as foreign, the body makes anti-HLA antibodies, that is, defenses aimed at them, and the graft, that is, the tissue that was put in, is damaged.
In brief
The HLA system, or human major histocompatibility complex, brings together more than 200 immune genes, all on the short arm of chromosome 6.
Three loci encode the class I molecules A, B and C, and three more encode class II, DR, DQ and DP; being codominant, every inherited allele is expressed.
The chance that two people express identical molecules is extremely low, and HLA molecules recognized as foreign trigger anti-HLA antibodies and graft damage.
It is a molecular ID badge: almost no two people carry the same combination.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingGenetics, Histocompatibility Antigen, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated