. >> reporter: in 2018, doctors discovered that cyndee's platelets had dropped to dangerous levels. >y living off of transfusions. >> reporter: her diagnosis, severe aplastic anemia. her immune system was attacking her bone marrow where blood cells are made. when treatments failed her only hope was a bone marrow transplant. >> they checked for a 10 out of 10 match on the be the match registry and didn't have one. >> reporter: for fortunately cyndee had three other options. half a match. how is it possible we can do a transplant with only a 50% match when for the previous three decades we required 100% match? the answer, advances in post-transplant drugs to prevent rejection. in november 2021 cyndee's son brian became her donor. >> he was able to give me life back. >> reporter: but there are many situations in which a happen low identical transplant is not the answer. >> that's why we like to continue informing the public about the importance of becoming a donor. >> reporter: being part of the registry is easier than ever. if you're between the ages of 18 and 40 you're eligible. it jus