He ate, played and learned like any other kid. But David Vetter's life unfolded in a series of unusual environments: plastic, bubblelike enclosures that protected him from germs. He had severe combined immunodeficiency (SCID), and even a seemingly harmless germ could kill him.
The subject of pop culture scrutiny and medical fascination, David was called "the boy in the bubble" by the media. SCID is rare and often fatal; it affects about 1 in 58,000 infants.
The disorder is created by genetic mutations that cause patients to produce too few of the immune cells that protect the body from infection. In healthy immune systems, T and B cells - known as lymphocytes - attack foreign organisms. People with SCID lack these critical immune defenses.
David, who lived in Texas, wasn't supposed to grow up in isolation. But while doctors waited for a cure, they decided to keep him in a sterile environment.