The Wisconsin State Laboratory of Hygiene, in conjunction with the University of Wisconsin, was chosen as the major testing site because of its long history of screening newborns for CF (21 ) and study of screening methods (22) (23) (24) (25) . In March 2002, DNA testing of the top 4% of the daily immunoreactive trypsinogen results expanded to include all 25 mutations recommended by the American College of Medical Genetics, the American College of Obstetricians and Gynecologists, and the NIH.