"It will be simple," said the dermatologist to the young man sitting in his office. "All you will have to do is follow a gluten-free diet, and later you may not have to take the medication that is causing you so much trouble." The physician's recommendation, given in 1973 to a relative I shall call Ron, amazed me. Ron had none of the signs and symptoms usually associated with gluten intolerance-that is, malabsorption of food; weight loss; and bulky, frothy, foul-smelling stools. Rather, his problems were dermatological: itching, burning skin blisters. Though his physicians had not been able to fully explain the nature of the disease to him, Ron had known its name for five years: dermatitis herpetiformis, or Duhring's disease. At the time Ron's condition was diagnosed, three different med-