Prader, Andrea (1919–2001), and Willi, Heinrich (1900–1971), Swiss pediatricians. Prader was a professor of pediatrics in Zurich. Her articles and chapters in textbooks dealt with such topics as genetics, growth, endocrinology, and metabolism in children and adolescents. Prader and Willi first described the Prader-Willi syndrome in 1956. Cases of the disorder were not diagnosed in the United States until the 1960s.