This innovation was the brainchild of four creative people. Dean Kamen, an inventor, had developed a set of small, portable, and very precise pumps. Dr. Howard Pearson, a pediatric hematologist who chaired the Department of Pediatrics at Yale, had been treating patients for a rare but serious blood disease, thalassemia major, with almost constant injections. Dr. Bart Kamen (Dean's brother), then a pediatrician in residency training at Yale, put together his brother's invention and Pearson's need for a method of constant infusion. Finally, another Yale faculty member, Dr. William Tamborlane, saw the small portable pump in action in the treatment of patients with thalassemia and understood its potential use in the treatment of diabetes.