Appeals like this always bother me. You can weed out incompatible donors by simply comparing blood types and yet no one ever posts compatible blood types or even their blood type. This seems like such a simple thing to do to increase your chances of finding a compatible donor.
There's always a limited number of free tests available but how many are wasted* on people with the wrong blood type? The tests are expensive and if someone knows up front they're not compatible but can afford to pay for a test, they might instead donate funds instead to purchase free tests for those that might be compatible but otherwise couldn't afford to get tested.
Here is who can donate to whom with regards to marrow transplants:
Type A can donate to types A and AB.
Type B can donate to types B and AB.
Type AB can donate to type AB.
Type O can donate to types A, B, AB, and O.
*I know that tests aren't wasted because the people are entered into a DB that benefits all marrow transplant recipients but the individual appealing to others for help could improve their odds.
That said, lots of people don't even know their blood types and that shouldn't be used as a barrier when the DB does need more ethnic diversity, period.
I understand the need for diversity in the database and you can argue that not filtering by blood type would expand the diversity, these appeals almost always ask for people of a particular race or heredity which limits diversity and seems to conflict with that notion of increasing diversity.
A compatible donor has to have a compatible blood type and matching leukocyte antigens. The later is expensive to test for but race can be used to exclude a large segment of incompatible donors. Blood type is harder to check obviously but compared to leukocyte antigen compatibility test it's cheap an easy. We're talking less than $10 vs $100+ for a leukocyte antigen test.
These are personal appeals and the two factors that can be used to cheaply and quickly narrow the field of potential donors the most are race and blood type compatibility.
Compatible donors need to have both a compatible blood type and the same leukocyte antigens. The later is usually dictated by your heredity and can only be determined by an expensive test. Race is the biggest qualifier that can be used to exclude segments of the population, blood type would be the second largest qualifier but they seem to skip this step and go straight for the expensive tests.
There's always a limited number of free tests available but how many are wasted* on people with the wrong blood type? The tests are expensive and if someone knows up front they're not compatible but can afford to pay for a test, they might instead donate funds instead to purchase free tests for those that might be compatible but otherwise couldn't afford to get tested.
Here is who can donate to whom with regards to marrow transplants:
*I know that tests aren't wasted because the people are entered into a DB that benefits all marrow transplant recipients but the individual appealing to others for help could improve their odds.