Medical treatment will be tailored to your genetic profile.
Your dirt-biking expedition has ended painfully-a few ribs broken in a tumble on the trail-and the emergency-room doctor has sent you home with a bottle of codeine. It should be enough to tide you over until the bones heal, unless you’re one of the 20 million Americans who have a mutated form of an enzyme called cyp2d6, which normally converts codeine into the morphine that soothes pain. If you are, the enzyme won’t work, and the pills won’t even take the edge off. Worse yet, neither you nor your physician will know that until you take the drug.