To all outward appearances, Ashanthi ("Ashi") DeSilva is a normal, healthy 12-year-old who loves sports and would rather play basketball than do her seventh-grade homework. But Ashi holds a unique place in medical history: she is the first recipient of successful gene therapy.
Ashi was born with a rare, inherited disorder called ADA deficiency, the disease that claimed the life of the famed "bubble boy" in 1984. Because of a faulty gene, the T cells of her immune system were unable to produce an enzyme, ADA, necessary for their survival. As they died off, Ashi's immune system virtually shut down, leaving...