As 12-year-old David Vetter was about to die at Texas Children's Hospital in 1984, he gave a last wink to his doctor, William T. Shearer. His wife told us Dr. Shearer carried that moment through the rest of his life. Dr. Shearer, a professor of pediatrics at Baylor College of Medicine, died this week at the age of 81. David Vetter had been born with severe combined immunodeficiency, a rare disease that could have made it fatal for him to be touched, held, kissed by his parents or even take a breath of fresh air. Doctors devised a sterile clear...