The genetic system that most influences the outcome of organ transplants is the Major Histocompatibility Complex (MHC), which in humans is also known as the HLA (Human Leucocyte Antigens) system. These genes are highly polymorphic, meaning that each individual in the population has inherited a set of genes that combine in an almost unique way. They encode cell surface glycoproteins which therefore vary from one individual to another and are recognized as a target in the case of transplantation by the recipient’s immune system.
It is considered that the right match for HLA characteristics between donor and recipient can explain less than half of the immunological causes of transplant failure. It is well known that differences in other genetic characteristics may be responsible for a not small share of transplant failure due to immunological causes. These characteristics are defined as minor histocompatibility genes (and antigen their products).
The new approaches to study the genome allow to examine all the variability of a recipient, and compare it with that of the donor: in this way it is possible to evaluate whether particular genetic collisions (i.e. incompatibility for some of them) can influence the outcome of the transplant. These studies made it possible to define new genes whose compatibility between donor and recipient may be relevant for the success of the transplant.
Keywords: transplants, genomics, histocompatibility