Are relatives always compatible for kidney transplant?

While relatives may be more likely to be compatible for kidney transplant due to shared genetics, it's not always the case that they are compatible. Compatibility for kidney transplantation depends on several factors, including blood type, tissue type, and the presence of antibodies. Even among relatives, there can be variations in these factors that may affect compatibility.

Blood type compatibility: For a successful kidney transplant, the blood type of the donor and recipient must be compatible. There are four main blood groups: A, B, AB, and O. A person can only receive a kidney from a donor with a compatible blood type.

Tissue type compatibility: Tissue type matching involves comparing the human leukocyte antigen (HLA) molecules of the donor and recipient. HLA molecules are proteins found on the surface of cells and play a crucial role in the immune system's ability to distinguish between self and non-self. The more closely matched the HLA molecules are between the donor and recipient, the less likely the recipient's immune system will reject the transplanted kidney.

Antibody crossmatch: An antibody crossmatch test is performed to determine if the recipient's immune system has developed antibodies that may attack the donor's kidney. If the crossmatch test is positive, indicating the presence of antibodies, the transplant is unlikely to be successful due to the high risk of rejection.

In some cases, relatives may not be compatible for kidney transplant due to differences in blood type, tissue type, or the presence of antibodies. In such situations, it may be necessary to seek a suitable donor from outside the family through a donor registry or paired donation programs.