Human leukocyte antigen (HLA) typing is used to match patients and donors for bone marrow or cord blood transplants (also called BMT). HLA are proteins — or markers — found on most cells in your body. Your immune system uses these markers to recognize which cells belong in your body and which do not.

A close match between your HLA markers and your donor's can reduce the risk that your immune cells will attack your donor's cells or that your donor's immune cells will attack your body after the transplant. If you need an allogeneic transplant (which uses cells from a family member, unrelated donor or cord blood unit), your doctor will take a blood sample to test for your HLA type.

HLA matching basics

A well-matched donor is important to the success of your transplant. You inherit half of your HLA markers from your mother and half from your father, so each brother and sister who has the same parents as you has a 25% chance of matching you. It is unlikely that extended family members will match you. However, your parents and/or children may also be tested to confirm your HLA typing and to make sure no possible donors are overlooked. About 70% of patients who need a transplant do not have a suitable donor in their family.

A close HLA match improves the chances for a successful transplant. Close matching:

Promotes engraftment- Engraftment is when the donated cells start to grow and make new blood cells.
Reduces the risk of a post-transplant complication called graft-versus-host disease (GVHD). - GVHD occurs when the immune cells from the donated marrow or cord blood (the graft) attack your body (the host).

PGD/PCR - HLA typing

It is now possible to undergo PGD for human leukocyte antigen (HLA) matching to you for the purpose of having a HLA-matched hematopoietic progenitor cell (HPC) donor for your Thalassemia affected child.. The PGD procedure allows genetic testing to be performed on early embryos before implantation and pregnancy development for the purpose of selecting only those embryos that are HLA matched to your affected child.

When a couple has a child with a single gene disorder like Thalassemia that requires an HPC transplant, the optimal source of cells needed for transplant is an HLA-matched sibling. Donors cells need to be HLA-matched to an affected child avoid any chance for the transplanted cells to react against the child’s body. If you undertake a natural pregnancy in the hope of having a child who is an HLA match to your affected child, there is 1 in 5 chance of conceiving a child who is an HLA match to the affected biological child.

Following IVF, Preimplantation genetic diagnosis can be used for selecting and transferring only the embryos that are HLA matched to your affected child. Each embryo has a 1 in 5 chance of matching the affected biological child. With PGD, the goal is to select those embryos that are a match and transfer them. In this process, we can significantly increase the chance to have a child that is HLA-matched to your affected child.

 

Alpha Thalassemia - Beta Thalassemia - Variant Hemoglobin