Donating bone marrow?

That physician is an idiot. There's no such thing as an "I don't know" when dealing with questions like this. Don't depend on anyone for this answer, because if a person is not a specialist in bone marrow transplant and oncology in general, they do not have the proper authority to answer your question. My advice would be to look in the yellow pages for the name of a physician who can help you, then call him/her up and ask your question. Better yet, go online and look up a clinic or hospital that deals with these issues.