Francis Collins was fresh off one of the most important scientific advances of all time—decoding a rough draft of the entire human genome—when he first met 4-year-old Sam Berns.
Sam did not look like a typical preschooler. His hair was falling out. He wasn't gaining weight. He was beginning to look like an old man. But as the two played catch in Collins's backyard, "it was clear that this was a wonderfully precocious little boy," Collins says.
The symptoms had shown up in the first few months of Sam's life, when his growth essentially stopped and his bones began to deteriorate. His parents tried doctor after doctor, test after test. Finally, they hit on Sam's diagnosis: progeria, a disease so rare that few of his doctors had seen it outside of a textbook. It affects only one in every 4 million to 8 million children.