Hi Beautiful thing to offer.
I'm in the field as a scientist.
You must match for your HLA type, both HLA-A, B, DR, DP and DQ. For a kidney the match does not have to be exact. It never is except in ID twins. Your risk: we have two kidneys for a reason. If one fails the other can cope, and cope well. If both fail; not good. If you donate a kidney you are putting your life at risk. If your single kidney fails you will need a transplant. That said, many people live with one kidney without dialysis. What you are offering your friend is gorgeous. You are offering life. The medics will take you through it, and do talk to the psychologist on the Unit. Sometimes the biggest problem is the person recieveng the graft. Dead peoples tissue, friends organs. Difficult to got