Timothy Ray Brown, shown in May 2011 with his dog Jack in San Francisco, is the only man ever known to have been fully cured from AIDS. Brown is known as the "Berlin patient" because he had a bone marrow transplant in a German hospital five years ago. Eric Risberg/AP hide caption

itoggle caption Eric Risberg/AP

Starting a bone marrow registry in Nigeria "became an obsession" for Seun Adebiyi. "I thought that even if I couldn't find a match, I wanted to make it easier for other black patients to find a match." Seun Adebiyi hide caption

itoggle caption Seun Adebiyi