SHORTLY AFTER THE BIRTH OF THEIR DAUGHTER KATIE, Steve and Stacy Trebing encountered every parent's worst nightmare: the discovery that their child had a devastating disease. Diagnosed with Diamond Blackfan anemia (DBA), a rare bone marrow affliction, Katie would have to bear a lifetime of monthly transfusions and daily injections unless she underwent a risky bone marrow transplant from a genetic match. But even if the Trebings...